The chief of the fire department, the chief of police or marshal of every incorporated city or town in which a fire department is established, the mayor of each incorporated town in which no fire department exists and the sheriffs of the several counties of the state shall be, by virtue of such offices so held by them, assistants to the Fire Marshal, subject to the duties and obligations imposed by this article and subject to the direction of the Fire Marshal in the execution of the provisions of this article.