Cal. Penal Code § 219.2

Every person who willfully throws, hurls, or projects a stone or other hard substance, or shoots a missile, at a train, locomotive, railway car, caboose, cable railway car, street railway car, or bus or at a steam vessel or watercraft used for carrying passengers or freight on any of the waters within or bordering on this state, is punishable by imprisonment in the county jail not exceeding one year, or in a state prison, or by fine not exceeding two thousand dollars ($2,000), or by both such fine and imprisonment.