Under the California Vehicle Code section 12517.1. (a) A “schoolbus (school bus) accident” means any of the following:
(1) A motor vehicle accident resulting in property damage in excess of seven hundred fifty dollars ($750) or personal injury, on public or private property, and involving a schoolbus, youth bus, school pupil activity bus, or general public paratransit vehicle transporting a pupil.
(2) A collision between a vehicle and a pupil or a schoolbus driver while the pupil or driver is crossing the highway when the schoolbus flashing red signal lamps are required to be operated pursuant to Section 22112.
(3) Injury of a pupil inside a vehicle described in paragraph (1) as a result of acceleration, deceleration, or other movement of the vehicle.
(b) The Department of the California Highway Patrol shall investigate all schoolbus accidents, except that accidents involving only property damage and occurring entirely on private property shall be investigated only if they involve a violation of this code.