In all cases of fire within the limits of the city or within one mile thereof during the time of fire, the chief of the fire department of the city or his assistant or any other person in command thereof at the time, shall for the purpose of extinguishing, controlling or checking such fire, have the right to enter any part of any building or structure within the limits aforesaid, and do or cause to be done therein, any act or thing he may deem necessary, and in extreme cases of fire, to explode or otherwise remove, or cause the same to be done, any building or structure within the limits aforesaid, and during the time of fire such person shall have the right to appoint special policemen, who shall have authority to act as such without being sworn.