The speed limitation set forth in this chapter shall not apply to vehicles when operated with due regard for safety under the direction of the police when traveling in emergencies or in the chase or apprehension of violators of the law or of persons charged with or suspected of a violation, nor to fire department or fire patrol vehicles when traveling in response to a fire alarm, nor to public or private ambulances when traveling in emergencies. This exemption shall apply only when the driver of the vehicle while in motion sounds an audible signal by bell, siren or exhaust whistle as may be reasonably necessary or when the vehicle is equipped with at least 1 lighted lamp displaying a flashing, oscillating or rotating red or blue light visible under normal atmospheric conditions from a distance of 500 feet to the front of such vehicles, unless the nature of the mission requires that a law enforcement officer travel without giving warning to suspected law violators. This exemption shall not however protect the driver of the vehicle from the consequences of a reckless disregard of the safety of others.