N.H. Rev. Stat. § 106-C:9
If, while any police department personnel or equipment pertaining to a New Hampshire county or municipality is engaged in rendering emergency police assistance upon call in another county or municipality within the state, an emergency develops within the county or municipality to which the assisting police department personnel and equipment pertain, the chief executive officer of such county or municipality shall determine whether such personnel and equipment shall be recalled in order to meet the local emergency. Upon the recall order issued by such chief executive officer of the assisting county or municipality, the personnel and equipment shall forthwith return to their normal stations or to the place specified in such recall order. The decision of the chief executive officer of the assisting county or municipality, made under the emergency conditions contemplated by this chapter, shall supersede any agreements or arrangements for mutual assistance entered into as provided in RSA 106-C:10.
RSA 106-C:9
1967, 431:1, eff. Sept. 5, 1967.