Cal. Veh. Code § 21055
The driver of an authorized emergency vehicle is exempt from Chapter 2 (commencing with Section 21350), Chapter 3 (commencing with Section 21650), Chapter 4 (commencing with Section 21800), Chapter 5 (commencing with Section 21950), Chapter 6 (commencing with 22100), Chapter 7 (commencing with Section 22348), Chapter 8 (commencing with Section 22450), Chapter 9 (commencing with Section 22500), and Chapter 10 (commencing with Section 22650) of this division, and Article 3 (commencing with Section 38305) and Article 4 (commencing with Section 38312) of Chapter 5 of Division 16.5, under all of the following conditions:
(b) If the driver of the vehicle sounds a siren as may be reasonably necessary and the vehicle displays a lighted red lamp visible from the front as a warning to other drivers and pedestrians.
A siren shall not be sounded by an authorized emergency vehicle except when required under this section.