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                                                                    Exhibit 10.4

                              EMPLOYMENT AGREEMENT

      This Agreement, made as of February 10, 2005 by and between Emergency
Medical Services L.P., a Delaware limited partnership (the "Company"), and Todd
Zimmerman (the "Executive").

                                    RECITALS

      WHEREAS, the Company has agreed to purchase all of the issued and
outstanding shares of common stock of (i) EmCare Holdings Inc., a Delaware
corporation and (ii) American Medical Response, Inc., a Delaware corporation;

      WHEREAS, Emergency Medical Services Corporation ("EMSC", the general
partner of the Company) has entered into that certain (i) Stock Purchase
Agreement, dated as of December 6, 2004 by and among Laidlaw International,
Inc., Laidlaw Medical Holdings, Inc. and EMSC (the "AMR Purchase Agreement") and
(ii) Stock Purchase Agreement, dated as of December 6, 2004 by and among Laidlaw
International, Inc., Laidlaw Medical Holdings, Inc. and EMSC (the "EmCare
Purchase Agreement" and together with the AMR Purchase Agreement, the "Stock
Purchase Agreements");

      WHEREAS, Executive is employed by EmCare (as defined below), which will
become a subsidiary of the Company on the Effective Date;

      WHEREAS, Executive is employed by EmCare, and will continue to be employed
by the Company, in a confidential relationship during which Executive has and
will become familiar with and aware of information as to the specific manner of
doing business, strategic plans for future business, and the identity of
customers of the Company and its subsidiaries, affiliates and managed entities,
all of which will be established and maintained at great expense to the Company,
all of which information is a trade secret and constitutes the valuable goodwill
of the Company;

      WHEREAS, Executive recognizes that the Company and its subsidiaries are
engaged in the business of medical transportation services, and physician
practice management services as related to hospital emergency department and
hospitalist outsourcing;

      WHEREAS, Executive recognizes that the Company and its subsidiaries and
managed entities depend upon a number of trade secrets (including secret
techniques, methods and data) in the course of providing services to their
clients and that the protection of these trade secrets is of critical importance
to the Company and its subsidiaries; and

      WHEREAS, the Company and its subsidiaries will sustain great loss and
damage if Executive should violate the provisions of this Agreement,
particularly with respect to confidential information and restrictions on
competition and that monetary damages for such losses would be extremely
difficult to measure.

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      NOW THEREFORE, in consideration of the mutual promises, terms, covenants
and conditions set forth herein and the performance of each, effective as of the
time of the Effective Date, it is hereby agreed as follows:

      1. Definitions:

      Whenever used in this Agreement, the following terms shall have the
meanings set forth below, and when the meaning is intended, the initial letter
of the word is capitalized:

            A. "Agreement" means this employment agreement, as amended from time
to time.

            B. "AMR" means American Medical Response, Inc., a Delaware
corporation and, on the Effective Date, a wholly owned subsidiary of the
Company.

            C. "Base Salary" means the salary of record paid to the Executive as
annual salary, as further indicated in paragraph (A) of Article 4.

            D. "Board" means the board of directors of the Company's general
partner unless the Company (or its successor) is then a corporation, in which
event it means the Company's board of directors.

            E. "Change in Control" means, during the Term, the sale of all or
substantially all of the assets of the Company.

            F. "Company" means Emergency Medical Services L.P., a limited
partnership formed under the laws of Delaware, and except where the context
requires otherwise, including all affiliates and Subsidiaries of the Company,
and any successor thereto.

            G. "Effective Date" means the Closing Date as defined in the Stock
Purchase Agreements.

            H. "EmCare" means EmCare Holdings Inc., a Delaware corporation and,
on the Effective Date, a wholly owned subsidiary of the Company.

            I. "Executive" means Todd Zimmerman.

            J. "15% Internal Rate of Return" means an Investor Return , in cash
or cash equivalent, at least equal to an amount determined by increasing the
amount of the initial investment, and all subsequent direct or indirect
investments by Onex, by the total compounded annual rate of return of 15%,
taking into account for these purposes the exercise of all options to purchase
Partnership Units outstanding under the Plan or otherwise (including, without
limitation, options, other equity awards or interests held by affiliates of Onex
and their respective employees), which are then exercisable or become
exercisable as a result of the realization of the 15% Internal Rate of Return.
Whether the 15% Internal Rate of Return has been realized shall be determined by
the Board whose decision shall be final and binding on the Executive. For the
avoidance of doubt, a 15% Internal Rate of Return shall be deemed realized only
if the Investor Return includes both the amount of the investments and the
required return on the investments.

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            K. "Investor Return" means the sum of all cash amounts actually
received by Onex, on a cumulative basis through the date of determination, in
the form of cash dividends, other distributions or sale proceeds in connection
with (a) a disposition of all or any part of its Partnership Units calculated
based on the actual net proceeds received from the disposition of such
Partnership Units (b) a disposition of all or substantially all of the assets of
the Company or a Subsidiary or (c) a recapitalization of the Company or any
Subsidiary. Such calculation shall take into account any transaction costs and
fees and shall exclude any management, consulting or other similar fees received
by Onex or its affiliates.

            L. "IPO/Recap" means an initial public offering of the equity of the
Company (an "IPO") or a recapitalization of the Company.

            M. "Liquidity Event" means (i) the sale of all, or substantially
all, of the Company's consolidated assets, including, without limitation, a sale
of all or substantially all of the assets of the Company or any of its
Subsidiaries whose assets constitute all or substantially all of the Company's
consolidated assets in any single transaction or series of related transactions
or (ii) any merger or consolidation of the Company with or into another entity
unless, after giving effect to such merger or consolidation, the holders of the
Company's Partnership Units (on a fully-diluted basis) immediately prior to the
merger or consolidation, own voting securities (on a fully-diluted basis) of the
surviving or resulting entity representing a majority of the outstanding voting
power to elect directors of the surviving or resulting corporation (or the
general partner of a surviving partnership) in the same proportions that they
held their Partnership Units prior to such merger.

            N. "Onex" means Onex Partners LP.

            O. "Partnership Units" means units representing limited partnership
interests in the Company.

            P. "Subsidiary" means any corporation that is a subsidiary of the
Company including, but not limited to EmCare and AMR.

      2. Employment.

            A. From the Effective Date, the Company shall employ the Executive
as General Counsel of EMSC, AMR and EmCare, and the Executive shall serve in
such capacity, performing such duties as are consistent with the position, along
with such other duties and responsibilities assigned to the Executive by the
Chief Executive Officer ("CEO") of EMSC. The Executive shall devote his best
efforts to the performance of his duties under this Agreement and shall perform
them faithfully, diligently, competently and in a manner consistent with the
policies of the Company as determined from time to time by the CEO.

            B. The Executive shall report to the CEO, and shall provide support
to the President of AMR or the President of EmCare, as applicable, on all
matters pertaining to his duties hereunder.

            C. The Executive shall not engage in other business activities
outside the scope of this Agreement, without the express approval of the CEO.

            D. The Executive shall not serve as an officer or director (or the
equivalent position) of any entity other than the Company or its affiliates or
managed entities, and shall not

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receive fees or other remuneration for work performed outside the scope of his
employment without prior written consent of the CEO.

      3. Term of Employment. This Agreement will be effective and binding
immediately upon its execution, but, anything in this Agreement to the contrary
notwithstanding, this Agreement shall not be operative until the Effective Date.
The Executive's employment under this Agreement shall commence on the Effective
Date, shall continue for a period of two years, and shall be renewed for
additional one year periods thereafter (each, a "Renewal Term") unless either
party informs the other in writing within 90 days of this Agreement's expiration
that it does not wish to renew the Agreement, or unless sooner terminated as
provided in this Agreement.

      4. Compensation.

            A. As full compensation for all services rendered by the Executive
pursuant to this Agreement, the Company shall pay, or shall cause a Subsidiary
to pay, to the Executive a salary of $325,000 per year ("Base Salary"), less
applicable withholdings. The Base Salary shall be payable twice monthly on the
15th business day and last business day of each month. Executive's compensation
shall be reviewed by the Board annually during the Company's normal review
period, beginning in the year following the first anniversary of the Effective
Date.

            B. The Executive will be eligible to participate in a short term
incentive plan. For fiscal years commencing September 1, 2004 and thereafter,
the Executive's target bonus under such plan will be 50% of Base Salary
(pro-rated for a partial fiscal year, including the first fiscal year in the
term). The Executive's right to receive any bonus under such plan shall be
determined based upon performance targets for each year fixed by the Board or a
duly authorized committee thereof; provided, that in the case of the partial
fiscal year beginning on the Effective Date the Executive's right to receive any
bonus under such plan shall be based on the achievement of the budget/business
plan of EmCare and AMR for the fiscal year beginning August 31, 2004 approved by
the board of directors of Laidlaw International, Inc.

            C. The Executive has agreed to co-invest in the Company on the
Effective Date, by purchasing the same securities purchased by the initial
equity investors at the per Partnership Unit price paid by the initial equity
investors, in the amount of $100,000,or such greater amount determined by the
Executive in his sole discretion. Concurrently with this co-investment by the
Executive, and pursuant to an equity option plan (the "Plan") the Company will
adopt, the Company will grant to the Executive options to purchase four-tenths
of one percent (0.4%) of the Partnership Units outstanding on the Effective Date
(the "Zimmerman Options"). For the avoidance of doubt, if the agreed-upon
co-investment is not made on the Effective Date, then the Company shall have no
obligation to grant the Zimmerman Options.

            The Zimmerman Options, if granted, will contain the following terms
and will otherwise be subject to the terms and provisions of the Plan:

                  1. Exercise Price. The exercise price will be the per unit
      purchase price paid by the initial equity investors in the Company.

                  2. Vesting and Exercisability.

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                        a. 50% of the Zimmerman Options will become vested and
      exercisable 25% on each of the first four anniversaries of the Effective
      Date without further condition.

                        b. 50% of the Zimmerman Options will become vested and
      exercisable 25% on each of the first four anniversaries of the Effective
      Date; provided, that exercisability is subject to the further condition
      that Onex has realized a 15% Internal Rate of Return.

                        c. Notwithstanding the provisions of clause (b), upon
      the occurrence of a Liquidity Event in which Onex realizes a 15% Internal
      Rate of Return, all of the Zimmerman Options shall become fully vested and
      exercisable on the occurrence of the Liquidity Event, and the Zimmerman
      Options shall terminate and be of no further force or effect if they are
      not exercised in connection with the Liquidity Event. For the purposes of
      this clause (c) only, the 15% Internal Rate of Return shall be determined
      based on (i) cash received by Onex at any time and/or (ii) the fair market
      value of assets received by Onex at any time (as such fair market value is
      determined by the Board). Any assets received by the Executive in the
      Liquidity Event shall be subject to the same restrictions (such as lock-up
      provisions) to which the assets received by Onex are subject.

                        d. On the fourth anniversary of the Effective Date, if
      the Zimmerman Options referred to in clause (b) have not terminated
      pursuant to clause (c) and have vested but are not exercisable because
      Onex has not realized a 15% Internal Rate of Return, then such Zimmerman
      Options shall also become exercisable if:

            (i)   the Company has met the Cumulative Cash Flow Test, as such
                  term will be defined in the Plan, or

            (ii)  if (x) the Company's common stock is publicly traded and
                  listed on a national securities exchange and (y) Onex would
                  have realized a 15% Internal Rate of Return if it had sold its
                  remaining common stock interest in the Company at a per share
                  price equal to the weighted average sale price of the Company
                  common stock (as quoted by such national securities exchange)
                  for any 30 consecutive trading days.

                  3. Term. For the avoidance of doubt, options that have vested
      according to paragraph 4.C.2.b (by acceleration or otherwise) upon the
      occurrence of a Liquidity Event but are not exercisable because Onex has
      not realized a 15% Internal Rate of Return shall terminate on the
      occurrence of the Liquidity Event, and be of no further force or effect.
      The occurrence of an IPO/Recap shall not affect the vesting of the
      Zimmerman Options.

      5. Fringe Benefits; Expenses.

            A. The Executive shall be entitled to welfare benefit coverages
(such as medical insurance, dental insurance, short and long-term disability
insurance and group term life insurance) to the same extent applicable to
similarly situated executives of the Company, in accordance with employee
benefit plans and policies maintained by the Company or a Subsidiary for the
benefit of the employees of the Company, and as amended from time to time.

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            B. The Company shall reimburse, or shall cause a Subsidiary to
reimburse, the Executive for all reasonable and necessary expenses, including
membership and licensing fees and dues, incurred by him in connection with the
performance of services hereunder, in accordance with the Company's policies and
procedures applicable to similarly situated executives of the Company.

            C. The Executive shall be entitled to such vacation time per
calendar year as is applicable to similarly situated executives of the Company,
which shall not be less than four weeks per calendar year, the use of which
vacation time shall be subject to prior approval by the CEO.

            D. The Company shall obtain and maintain directors and officers
liability insurance policies covering Executive's actions hereunder on the same
terms as similarly situated executives of the Company.

            E. In the event Executive moves his place of primary residence from
Dallas, Texas to Denver, Colorado at the Company's request, Company shall pay
all reasonable and customary moving and transportation expenses in connection
with such relocation.

            F. Company shall provide Executive with a monthly allowance in the
amount of $600 to reimburse Executive for automobile expenses.

      6. Disability or Death.

            A. If, as the result of any physical or mental disability, the
Executive shall have failed or is unable to perform his duties for a period of
180 consecutive days, the Company may, by notice to the Executive subsequent
thereto, terminate this Agreement as of the date of the notice without any
further payment or the furnishing of any benefit by the Company under this
Agreement, unless otherwise required by applicable law. During the period of
disability, and prior to notice of termination by the Company as provided in the
preceding sentence, Executive shall be entitled to receive his base salary and,
if the performance targets are met, a pro rata portion of his annual performance
bonus payable pursuant to paragraph 4.B; such amounts shall be reduced by any
amounts paid to Executive under disability insurance policies maintained by the
Company.

            B. The term of the Executive's employment under this Agreement shall
terminate upon his death without any further payment or the furnishing of any
benefit by the Company under this Agreement (other than accrued and unpaid Base
Salary and expenses and benefits which have accrued pursuant to any plan or by
law).

      7. Termination.

            A. The Company shall have the right to terminate this Agreement
immediately for cause in the event of the occurrence of any of the following:

                  1. Fraud, theft, gross misconduct or gross negligence on the
      part of the Executive, including, without limitation, conduct of a
      felonious or criminal nature, conduct involving moral turpitude,
      embezzlement, misappropriation of assets or substantial neglect of duties;

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                  2. Alcohol or drug abuse that impairs the Executive's ability
      to properly perform his duties;

                  3. Violation of the Company's Corporate Compliance Policy; or

                  4. A material breach of the Agreement by the Executive which
      has not been cured within 30 days of receipt by Executive of written
      notice of the breach.

            B. Either party may terminate this Agreement without cause by
providing the other party with 90 days prior written notice of termination. If
termination is by Executive, the Company may waive notice, in whole or in part,
upon immediate payment to the Executive of the Executive's Base Salary for such
portion of the 90-day notice period as is waived by the Company. Upon such
termination, the Company may elect, in its sole and absolute discretion, to pay
the Executive his Base Salary in effect at the time of such termination for a
period of up to 18 months following such termination as consideration for
Executive's agreement set forth in paragraph 9.A.

            C. Executive may terminate this Agreement in the event of a material
breach of the Agreement by the Company which has not been cured within 30 days
of receipt by the Company of written notice of the breach.

            D. The Executive may terminate employment with the Company and any
Subsidiary with the right to severance compensation as provided in paragraph
8.B. upon the occurrence of a Change in Control followed by one or more of the
following events:

                  1. Failure to elect or reelect or otherwise to maintain the
      Executive in the office or position, or a substantially equivalent office
      or position, of or with the Company which the Executive held immediately
      prior to the Change in Control;

                  2. (a) A significant adverse change in the nature or scope of
      the authorities, powers, functions, responsibilities or duties attached to
      the position with the Company which the Executive held immediately prior
      to the Change in Control, (b) a reduction in the aggregate of the
      Executive's Base Salary received from the Company or the value of the
      Executive's incentive pay opportunity from the Company or its
      Subsidiaries, or (c) the termination of the Executive's rights to employee
      benefits or a reduction in the scope or value thereof to a level that is
      substantially lower in the aggregate from the level in effect at the time
      of the Change in Control, any of which is not remedied by the Company with
      10 calendar days after receipt by the Company of written notice from the
      Executive of such change, reduction, or termination, as the case may be;
      or

                  3. The liquidation, dissolution, merger, consolidation or
      reorganization of the Company or transfer of all or substantially all of
      its business and/or assets, unless the successor or successors (by
      liquidation, merger, consolidation, reorganization, transfer or otherwise)
      to which all or substantially all of its business and/or assets have been
      transferred (by operation of law or otherwise) assumed all duties and
      obligations of the Company.

                                        7
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      8. Salary/Benefit Continuation.

            A. Upon termination of this Agreement by the Company for cause or in
the event of the Executive's termination of this Agreement without cause,
Executive shall be entitled to receive all salary earned under this Agreement up
to the date of termination.

            B. Upon termination of this Agreement by the Company without cause
or in the event of the Executive's termination of this Agreement in accordance
with paragraph 7.C, the Executive shall be entitled to receive the following:

                  1. All salary earned under this Agreement up to the date of
      termination; and

                  2. Base compensation at the rate payable on the date
      immediately prior to termination for an additional period of 18 months
      (or, in any Renewal Term, for the number of months remaining in the
      Renewal Term, or, in Purchaser's sole and absolute discretion, for a
      longer period, up to a maximum of 18 months); and

                  3. For a period of 18 months following the date of termination
      (or, in any Renewal Term, for the number of months remaining in the
      Renewal Term, or, in Purchaser's sole and absolute discretion, for a
      longer period, up to a maximum of 18 months), the Company shall continue
      to pay for the cost of Executive's participation in the Company's group
      medical and dental insurance plans and group life insurance at the same
      rate as applicable to Executive immediately prior to termination, provided
      that Executive is entitled to continue such participation under applicable
      state and federal law and under the terms of the Company's employment
      benefit plans in effect at the time (including provisions in the Company's
      medical and dental plans related to coordination with other insurance, as
      applicable); and

                  4. If the performance targets for the year are met, a pro rata
      portion (equal to a fraction, of which the numerator is the number of full
      months of Executive's employment in the year and the denominator is 12),
      of the bonus payable to Executive pursuant to paragraph 4.B., payable at
      such time as the Company pays annual incentive bonuses for the year to
      executives of the Company.

            C. Upon termination of this Agreement by Executive in accordance
with paragraph 7.D, the Executive shall be entitled to receive the compensation
set forth in paragraphs 8.B.1, 8.B.2 and 8.B. 3.

            D. As a condition to receipt of the items set forth in paragraph
8.B.2, 8.B.3 and 8.B.4, as applicable, Executive shall execute promptly upon
termination a Settlement and Release Agreement, pursuant to which Executive
shall release the Company from any and all claims and demands which Executive
may possess against the Company.

      9. Restrictive Covenants.

            A. Executive agrees that during the term of this Agreement, and for
18 months thereafter (provided, that if Executive does not receive severance
benefits upon termination of this Agreement, such period shall be 12 months),
Executive will not in any manner, without the prior written consent of the
Company, directly or indirectly: (1) disclose or divulge to any person, entity,
firm, company or employer, or use for Executive's own benefit or

                                        8
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the benefit of any other person, entity, firm, company or employer directly or
indirectly in competition with the Company, any knowledge, information, business
methods, techniques or data of the Company; (2) solicit, divert, take away or
interfere with any of the customers, accounts, trade, business patronage,
employees or contractual arrangements of the Company; (3) compete with the
Company or enter into any contractual arrangements for the provision of medical
transportation services, and physician practice management services as related
to hospital emergency department and hospitalist outsourcing with any
governmental authority, provider or hospital with which Executive has come into
contact while an employee of the Company; or (4) either individually or in
partnership, or jointly in conjunction with any other person, entity or
organization, as principal, agent, consultant, lender, contractor, employer,
employee, investor, shareholder, or in any other manner, directly or indirectly,
manage, carry on, establish, control, engage in, invest in, offer financial
assistance, financial services to, or permit his name to be used by any business
that competes with the then-existing business of the Company, provided that the
Executive shall be entitled, for investment purposes, to purchase and trade
shares of a public company which are listed and posted for trading on a
recognized stock exchange and the business of which public company may be in
competition with the business of the Company, provided that the Executive shall
not directly or indirectly own more than five percent (5%) of the issued share
capital of the public company, or participate in its management or operation, or
in any advisory capacity within the time limits set out herein. Solely for the
purposes of this paragraph 9, the term "Company" shall mean the Company, its
subsidiaries, its affiliates, their subsidiaries and companies for whom such
entities provide services.

            B. Executive further agrees that for a period of 18 months following
termination of employment, however caused, he will not solicit for hire or
rehire, or take away, or cause to be hired, or taken away, management level
employee(s) of the Company.

            C. It is the intention of the parties to restrict the activities of
Executive in a manner which reasonably protects the legitimate business
interests of the Company. In the event this paragraph 9 is deemed overly broad
or unenforceable by a court of competent jurisdiction, it is the intent of the
parties that this paragraph be enforced to the fullest extent allowed under
applicable law, and be reformulated by such court to the extent necessary to so
enforce it.

            D. Executive agrees that the damages and remedies at law for any
breach under this paragraph would be inadequate and that, in addition, in the
event of a breach under this paragraph, the Company may apply to a court of
competent jurisdiction and be entitled to an injunction by such court to prevent
a breach or further breach thereof on the part of the Executive. Such injunction
shall be in addition to damages or other relief afforded under this Agreement.

            E. The Executive acknowledges that the agreements provided in this
Section 9 were an inducement to the Company to enter into this Agreement and
that the remedy at law for breach of his covenants under this Section 9 will be
inadequate. Accordingly, in the event of any breach or threatened breach by the
Executive of any provision of this Section 9, the Company shall be entitled, in
addition to all other remedies, to an injunction restraining any breach by
Executive.

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      10. Miscellaneous.

            A. This Agreement shall become operative automatically on the
Effective Date and, as of the Effective Date, shall constitute the entire
agreement between the parties with respect to the employment and appointment of
the Executive and any and all previous agreements, written or oral, express or
implied, between the parties or on their behalf, relating to the employment and
appointment of the Executive by the Company or any Subsidiary, are terminated
and cancelled effective on the Effective Date and each of the parties releases
and forever discharges the other of and from all manner of actions, causes of
action, claims and demands whatsoever, under or in respect of any previous
agreement, including without limitation, the Agreement, dated as of June 30,
2002, and amended November 6, 2004, between EmCare and the Executive which is
hereby terminated and cancelled effective on the Effective Date. If the
Effective Date does not occur on or before March 31, 2005, this Agreement shall
become null and void and of no further force and effect.

            B. This Agreement shall be governed by and construed in accordance
with the laws of the State of Delaware applicable to agreements made and
performed in Delaware, and shall be construed without regard to any presumption
or other rule requiring construction against the party causing the Agreement to
be drafted.

            C. This Agreement cannot be modified, amended, or terminated orally.
Amendments may be made to this Agreement at any time if mutually agreed upon in
writing.

            D. Any amendment, notice, or other communication under this
Agreement shall be in writing and shall be considered given when received and
shall be delivered personally or mailed by certified mail, return receipt
requested, to the parties at their respective addresses set forth below (or at
such other address as a party may specify by notice to the other):

            If to Company:     Emergency Medical Services L.P.
                               c/o Onex Investment Corporation
                               New York, New York 10019
                               Attention: Robert M. Le Blanc, President
                               Facsimile: (212) 582-0909

            If to Executive:   Last known address on file with the Company

            E. The failure of a party to insist upon strict adherence to any
term of this Agreement on any occasion shall not be considered a waiver or
deprive that party of the right thereafter to insist upon strict adherence to
that term or any other term of this Agreement. Any waiver must be in writing.

            F. The invalidity or unenforceability of any term or provision of
this Agreement shall not affect the validity or enforceability of the remaining
terms or provisions of this Agreement which shall remain in full force and
effect and any such invalid or unenforceable term or provision shall be given
full effect as far as possible. If any term or provision of this Agreement is
invalid or unenforceable in one jurisdiction, it shall not affect the validity
or enforceability of that term or provision in any other jurisdiction.

            G. This Agreement is not assignable by either party except that it
shall inure to the benefit of and be binding upon any successor to the Company
by merger or consolidation

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or the acquisition of all or substantially all of the Company's assets, provided
such successor assumes all of the obligations of the Company, and shall inure to
the benefit of the heirs and legal representatives of the Executive.

            H. The parties acknowledge that none of the benefits granted to
either party here under are conditioned on any requirement that either party
make referrals to, be in a position to make or influence referrals to, or
otherwise generate business for the other.

            I. If the Executive is made a party to any action, suit, proceeding
or any other claim whatsoever, by reason of the fact that the Executive is or
was a director, officer, employee or agent of the Company and one or more
Subsidiaries, or is or was serving at the request of Company and one or more
Subsidiaries, as a director, officer, employee or agent of another corporation,
partnership, joint venture, trust or other enterprise, whether or not the basis
of such claim is the Executive's alleged action in an official capacity while in
service as a director, officer, employee or agent of the Company and one or more
Subsidiaries the Executive shall be indemnified and held harmless by the Company
and one or more Subsidiaries to the fullest extent legally permitted or
authorized by the Company's and such Subsidiaries' certificate of incorporation
or bylaws or resolutions of the Board against all expenses, liability and loss,
including, without limitation, legal fees, fines or penalties and amounts paid
or to be paid in settlement, all as reasonably incurred by the Executive in
connection therewith, and such indemnification shall continue as to the
Executive even after the Executive has ceased to be a director, officer,
employee or agent of the Company or such Subsidiaries, and shall inure to the
benefit of the Executive's heirs, executors and administrators.

                            [signature page follows]

                                       11
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      IN WITNESS WHEREOF, the Company and Executive have executed this
Agreement, in multiple counterparts, each of which shall be deemed an original,
effective the day and year first above written.

                                            Emergency Medical Services L.P.

                                            By: Emergency Medical Services
                                                Corporation, its general partner

                                            By: /s/ Robert M. LeBlanc
                                                --------------------------------
                                                Name: Robert M. Le Blanc
                                                Title: President

                                            Date of Execution: February 9, 2005

                                            /s/ Todd Zimmerman
                                            ------------------------------------
                                            Todd Zimmerman

                                            Date of Execution: February 9, 2005

               [signature page to Zimmerman employment agreement]

                                       12
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                            ASSIGNMENT AND ASSUMPTION

            This Assignment and Assumption, dated as of February 10, 2005,
between Emergency Medical Services Corporation, a Delaware corporation ("EMSC")
and Emergency Medical Services L.P., a Delaware limited partnership ("EMS").

            Reference is made to (i) the Employment Agreement, dated as of
February 10, 2005, between EMS and Don S. Harvey (the "HARVEY AGREEMENT"); (ii)
the Employment Agreement, dated as of February 10, 2005, between EMS and Randel
G. Owen ( the "OWEN AGREEMENT"); and (iii) the Employment Agreement dated as of
February 10, 2005, between EMS and Todd Zimmerman (together with the Harvey
Agreement and the Owen Agreement, the "EMPLOYMENT AGREEMENTS").

            EMS wishes to assign to EMSC, and EMSC wishes to accept and assume
from EMS, EMS's rights and obligations and Employment Agreements.

            NOW THEREFORE, intending to be legally bound, the parties hereby
agree as follows:

            EMS hereby assigns, transfers, grants and otherwise conveys to EMSC,
and EMSC hereby accepts and assumes from EMS, all of the rights and obligations
under the Employment Agreements.

                                      * * *

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<PAGE>

            IN WITNESS WHEREOF, the parties hereto have caused this Assignment
and Assumption to be executed and delivered as of the date first written above.

                                     EMERGENCY MEDICAL SERVICES CORPORATION

                                     By: /s/ Randy Owens
                                         ---------------------------------------
                                         Name: Randy Owens
                                         Title: CFO

                                     EMERGENCY MEDICAL SERVICES L.P.

                                     By: Emergency Medical Services Corporation,
                                         its general partner

                                     By: /s/ Randy Owens
                                         ---------------------------------------
                                         Name: Randy Owens
                                         Title: CFO

                                       14