Cal. Pen. Code § 243.3
When a battery is committed against the person of an operator, driver, or passenger on a bus, taxicab, streetcar, cable car, trackless trolley, or other motor vehicle, including a vehicle operated on stationary rails or on a track or rail suspended in the air, used for the transportation of persons for hire, or against a schoolbus driver, or against the person of a station agent or ticket agent for the entity providing the transportation, and the person who commits the offense knows or reasonably should know that the victim, in the case of an operator, driver, or agent, is engaged in the performance of his or her duties, or is a passenger the offense shall be punished by a fine not exceeding ten thousand dollars ($10,000), or by imprisonment in a county jail not exceeding one year, or by both that fine and imprisonment. If an injury is inflicted on that victim, the offense shall be punished by a fine not exceeding ten thousand dollars ($10,000), or by imprisonment in a county jail not exceeding one year or in the state prison for 16 months, or two or three years, or by both that fine and imprisonment.
Ca. Pen. Code § 243.3