R.I. Gen. Laws § 45-42-1: Emergency police power.

(a) When the police chief of a city or town within the state, or his or her designee, requests emergency police assistance from another city or town police department within the state, the officers responding to the request shall be subject to the authority of the requesting chief and have the same authority, powers, duties, privileges, and immunities as a duly appointed police officer of the city or town making the request, until the requesting chief of police discharges and releases the assisting police officers to their own city or town departments.

(b) Law enforcement officers from out of state shall have limited emergency police powers to transport, guard, and maintain custody of any person who is arrested out of state but transported to a Rhode Island medical facility for emergency medical treatment. Prior to entry into Rhode Island, the out-of-state police department maintaining custody of said arrested person shall notify the Rhode Island state police of the transport and the site of the emergency medical treatment. The emergency police powers granted shall cease immediately upon the expiration of eight (8) hours from the time of notification, or upon a fugitive-from-justice warrant being executed, whichever shall arise first.