N.H. Rev. Stat. Ann. § 154:9

If any person present at a fire, emergency or service call, at or to which the fire department is responding shall refuse or neglect to obey the commands of any member who is recognized as, or should have been recognized as, a member of the fire department, or shall unlawfully assume the office or badge of office of a fire chief, fire officer or firefighter, such person shall be guilty of a violation.