35 Pa. C.S. § 7331
The purpose of this subchapter is to create a system of intrastate mutual aid between participating political subdivisions within this Commonwealth, whereby each participating political subdivision recognizes that emergencies transcend the boundaries of a political subdivision and that intergovernmental coordination is essential for the protection of lives and property and for the best use of available public and private assets. The system shall provide for mutual assistance among the participating political subdivisions in the prevention of, response to and recovery from threats to public health and safety that are beyond the capability of an affected community to respond. The system shall provide for mutual cooperation among the participating subdivisions in conducting exercises, testing or other training activities.
35 Pa.C.S. § 7331