Any person employing persons and working them in buildings is forbidden to lock such employees in such buildings when by so doing they become endangered by fire. But the provisions of this section shall not apply to any building or room that may be locked so as to be opened from the inside by any employee of ordinary intelligence. The sheriff, constables and all other law enforcing officers shall see that the provisions hereof are observed and shall prosecute all violations thereof called to their attention or discovered by them. Any violation hereof shall be a misdemeanor and the violator shall be subject to a fine of not less than fifty dollars, nor more than one thousand dollars, or not exceeding six months in prison in the discretion of the court.