<PAGE>
 
105822

                                                                   Exhibit 10(a)




                     FIRST AMENDMENT TO EMPLOYMENT AGREEMENT
                     ---------------------------------------



                  THIS AGREEMENT made as of September 15, 1997, between HERITAGE
BANCORP, INC., a Pennsylvania corporation formerly known as Miners National
Bancorp, Inc. ("Employer"), having an office at 120 South Centre Street,
Pottsville, Pennsylvania 17901, and ALLEN E. KIEFER, with an address at R.D. #3,
Box 155, Schuylkill Haven, Pennsylvania 17972 ("Executive").

                             W I T N E S S E T H:

                  WHEREAS, Executive and Employer are parties to that certain
Employment Agreement dated as of September 13, 1994 pursuant to which Executive
has been employed as President and Chief Executive Officer of Employer and
Heritage National Bank (formerly The Miners National Bank), a wholly-owned
subsidiary of Employer (the "Bank"); and

                  WHEREAS, Employer and Executive desire to extend the terms of
said Employment Agreement and make certain other amendments as set forth herein.

                  NOW, THEREFORE, in consideration of the mutual promises set
fort herein and in said Employment Agreement and intending to be legally bound,
the parties hereto hereby agree as follows:

                  1. The "Term" of Executive's employment under said Employment
Agreement (said Employment Agreement as amended hereby is hereinafter referred
to as the "Employment Agreement") as provided in Section 2(a) is hereby extended
until September 30, 2000 and all references in the Employment Agreement to the
Term shall include the Term as extended hereby.
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                  2. The first sentence of Section 2(b) of the Employment
Agreement is hereby amended to read as follows: "Executive's employment right
hereunder shall automatically terminate at the close of business on September
30, 2000.

                  3. Executive's annual base salary during the remainder of the
Term shall be at least equal to executive's base salary currently in effect,
subject to increase by Employer from time to time with the approval of the Board
of Directors of Employer.

                  4. Section 6(c) of the Employment Agreement is hereby amended
to read as follows:

                     (c) Other Benefits. Executive acknowledges that, in the
                         --------------
         event of termination of Executive's employment during the Term of his
         employment hereunder pursuant to paragraph (a) of this Section 6, the
         payments and benefits to be made or provided to Executive pursuant to
         this Section 6 are to be in full satisfaction of Employer's obligations
         to Executive under this Employment Agreement and Executive shall not be
         entitled to any other severance or termination benefits, whether
         pursuant to this Employment Agreement or otherwise; provided, however,
                                                             --------  -------
         that this paragraph (c) shall not be deemed to affect Executive's
         rights to payments or benefits under any existing or future benefit
         plan or arrangement (other than a severance or termination plan or
         arrangement) of the Corporation, the Bank or any successor in which
         Executive is or becomes a participant, or under which Executive has or
         obtains rights, including, without limitation, any qualified or
         nonqualified deferred compensation or retirement plans or programs or
         any outstanding stock options or similar agreements. Any such rights of
         Executive shall be determined in accordance with the terms and
         conditions of the applicable agreement, arrangements or plan and
         applicable law. Notwithstanding the foregoing, if during the Term
         Executive becomes entitled to receive benefits under any change in
         control agreement then in effect as a result of the termination of
         Executive's employment following a change in control event specified in
         said agreement, the benefits to be provided under such change in
         control agreement shall control and Executive shall not be entitled to
         also receive termination benefits under this Employment Agreement.

                  5. Section 7 of the Employment Agreement is hereby amended by
deleting it in its entirety.



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                  6. The terms of the Employment Agreement dated September 13,
1994, as amended hereby, shall remain in full force and effect from and after
the date hereof.

                  IN WITNESS WHEREOF, the following have caused their signatures
and seals to be hereunto affixed to this Amendment as of the date first above
written.


ATTEST:                                HERITAGE BANCORP, INC.


/s/  Beverly A. Riotto                 By: /s/  Richard A. Ketner
---------------------------               ------------------------------
(Assistant) Secretary
(SEAL)




WITNESS:                               EXECUTIVE


/s/  David L. Scott                    /s/  Allen E. Kiefer               
---------------------------            ------------------------------(SEAL)
                                       Allen E. Kiefer








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