N.H. Rev. Stat. § 106-C:6
Neither the state nor any county or municipality whose police department personnel, pursuant to the provisions of this chapter, are rendering emergency police assistance to another county or municipality, shall be liable by reason of any act or omission on the part of such police department personnel while so engaged; or on account of the maintenance or use of any equipment or supplies used in connection with the rendering of such assistance; nor shall any county commissioner, police commissioner, sheriff, police chief or other superior officer of any police department, sheriff's office or the state police, acting pursuant to the provisions of this chapter, be liable by reason of any act or omission on the part of any of his subordinates when they are rendering emergency assistance, under the command of an officer other than himself, in a county or municipality other than that in which they normally are employed.
RSA 106-C:6
1967, 431:1, eff. Sept. 5, 1967.