Cal. Code Regs. tit. 2 § 5052
Provisions of these regulations governing the operation, parking or standing of vehicles in the park and the adjacent parking facilities shall not apply to any vehicle of the police or fire department, any public ambulance, or any public utility vehicle, or any private ambulance which public utility vehicle or ambulance has qualified as an authorized emergency, when any vehicle mentioned in this section is operated in the manner specified in the Vehicle Code in response to an emergency call. The foregoing exemptions shall not, however, protect the driver of any vehicle of the consequences of his willful disregard of the safety of others. The provisions of these regulations governing the parking or standing of vehicles shall not apply to any vehicles of the city, county, state or federal government or public utility while necessary and used for construction or repair work or while engaged in the collection of garbage or noncombustible rubbish where compliance therewith would obstruct such operation or any vehicle owned by United States while in use for the collection, transportation or delivery of United States mail or to any vehicle owned or operated by the Department of Army, Department of Navy or Department of Air Force during periods of proclaimed national emergency.
Cal. Code Regs. Tit. 2, § 5052