Veh. Code, § 25279

(a) Vehicles owned and operated by private security agencies and utilized exclusively on privately owned and maintained roads to which this code is made applicable by local ordinance or resolution, may display flashing amber warning lights to the front, sides, or rear, while being operated in response to emergency calls for the immediate preservation of life or property.

(b) (1) Vehicles owned by a private security agency and operated by personnel who are registered with the Department of Consumer Affairs under Article 3 (commencing with Section 7582) of Chapter 11.5 of Division 3 of the Business and Professions Code may be equipped with a flashing amber warning light system while the vehicle is operated on a highway, if the vehicle is in compliance with Section 27605 and is distinctively marked with the words “PRIVATE SECURITY” or “SECURITY PATROL” on the rear and both sides of the vehicle in a size that is legible from a distance of not less than 50 feet.

(2) The flashing amber warning light system authorized under paragraph (1) shall not be activated while the vehicle is on the highway, unless otherwise directed by a peace officer, as defined in Chapter 4.5 (commencing with Section 830) of Title 3 of Part 2 of the Penal Code.

(c) A peace officer may order that the flashing amber warning light system of a vehicle that is found to be in violation of this section be immediately removed at the place of business of the vehicle’s owner or a garage.

(d) A flashing amber warning light system shall not be installed on a vehicle that has been found to be in violation of this section, unless written authorization is obtained from the Commissioner of the California Highway Patrol.