Your landlord insurance policy extends only to that which you own. Therefore, unless you are found liable for any damages to your tenants' property, your insurance policy will not cover the items your renters keep in the home or unit.
Many landlords choose to require their tenants to purchase renters insurance as part of their lease agreement. This not only ensures your renters are covered in the case of fire or theft, but it can also help prevent renters from trying to sue you for damages.