Any authorized emergency vehicle may be equipped with a siren, whistle or bell capable of emitting sound audible under normal conditions from a distance of not less than 500 feet and of a type approved by the Department, but the siren shall not be used except when the vehicle is operated in response to an emergency call or in the immediate pursuit of an actual or suspected violator of the law, in which latter event the driver of the vehicle shall sound the siren when necessary to warn pedestrians and other drivers of the approach thereof.
(1982 Code, Ch. 4, Art. II, § 3-6)