No person shall fire any cannon, gun, air gun, spring gun, rifle, pistol or firearms of any kind within the limits of the City, provided that nothing herein shall be held to apply to any military company when drilling under command of an officer thereof or to regular shooting clubs, or shooting galleries having written permit from the Mayor, or targets privately erected for practice when permitted in writing by the Mayor, or to the use of firearms in the lawful defense of the person, family or property of any person, or by any police officer in the lawful discharge of his duties. (Ord. 6439. Enacted 9-17-56.)