It shall be the duty of the officers of the division of police, and such officers as are assigned by the police chief to enforce all street traffic laws of the urban county government and all of the state vehicle laws applicable to street traffic in the urban county. Officers of the division of police and such officers as are assigned by the police chief are hereby authorized to direct all traffic by voice, hand or signal in conformance with traffic laws; provided, in the event of a fire or other emergency or to expedite traffic or to safeguard pedestrians, officers of the division of police may direct traffic as conditions may require, notwithstanding the provisions of the traffic laws. Officers of the division of fire and emergency services, when at the scene of a fire, or when enroute to the scene of a fire, may direct or assist the police in directing traffic thereat or in the immediate vicinity.