N.H. Rev. Stat. § 21-P:40
The local director of each local organization for emergency management may, with the approval of the commissioner and in collaboration with other public and private agencies within this state, develop or cause to be developed mutual aid arrangements for reciprocal emergency management aid and assistance in case of disaster too great to be dealt with unassisted. Such arrangements shall be consistent with the state emergency management plan and program, and in time of emergency it shall be the duty of each local organization for emergency management to render assistance in accordance with the provisions of such mutual aid arrangements. Parties shall be entitled to the same immunities and exemptions as provided in RSA 21-P:41.
RSA 21-P:40
2002, 257:7, eff. July 1, 2002.