During the period of any blackout all pedestrian traffic within the city is hereby prohibited and declared unlawful and immediately upon the sounding of any air raid alarm pedestrians shall take shelter; provided, that this restriction shall not apply to any firemen, police officers, members of the armed forces of the United States of America or Idaho state guard, duly licensed physicians, surgeons and nurses and other officially authorized persons, if and when acting in the line of their respective duties. (1961 Code)