Vehicle Code § 27003
ARTICLE 1. Horns, Sirens and Amplification Devices
An armored car may be equipped with a siren which may be used while resisting armed robbery. At all other times, the siren shall not be sounded. The authority to use a siren granted by this section does not constitute an armored car an authorized emergency vehicle, and all other provisions of this code applicable to drivers of vehicles apply to drivers of armored cars.