Whenever three or more municipalities within the state vote to authorize their respective fire departments to render outside aid as provided in sections 2981 through 2985 of this title, they may, if they so desire, form a district fire mutual aid system, which shall be a public municipal corporation. They may petition the state fire marshal in writing to call the organization meeting of the system. (1967, No. 255 (Adj. Sess.), § 6, eff. Feb. 20, 1968.)