California Code, Vehicle Code - VEH § 25275.5

Any bus operated either by a public agency or under the authority of a certificate of public convenience and necessity issued by the Public Utilities Commission may be equipped with a system of crime alarm lights.  The system of crime alarm lights shall consist of the installation of additional lamp sources, not exceeding 32 standard candlepower or 30 watts, in the front and rear clearance lamps required or permitted by Section 25100.  Such lamps shall be operated by a flasher unit or units that are not audible inside the bus.  When actuated, both rear crime alarm lights shall flash simultaneously and both front crime alarm lights shall flash simultaneously.  Crime alarm lights shall be actuated only when a crime is in progress on board the bus or has recently been committed on board the bus.