Every municipal corporation which owns, operates, or maintains fire apparatus and equipment may permit, under conditions prescribed by the governing body of such corporation, such equipment and the personnel operating the same to go outside of the corporate limits of such municipality for the purpose of extinguishing or aiding in the extinguishing or control of fires. Any use made of such equipment or personnel under the authority of this section shall be deemed an exercise of a governmental function of such municipal corporation.
RCW 35.84.040