§ 71. Liability for damages by mobs and riots. A city or county shall be liable to a person whose property is destroyed or injured therein by a mob or riot, for the damages sustained thereby, if the consent or negligence of such person did not contribute to such destruction or injury, and such person shall have used all reasonable diligence to prevent such damage, shall have notified the mayor of the city, or sheriff of the county, of a threat or attempt to destroy or injure his property by a mob or riot, immediately upon acquiring such knowledge, and shall bring an action therefor within three months after such damages were sustained. A mayor or sheriff receiving notification of a threat or attempt to destroy or injure property by a mob or riot shall take all lawful means to protect such property; and if he shall neglect or refuse, the person whose property shall be destroyed or injured, may elect to bring his action for damages against such officer instead of the city or county.