The blaze was reported at 11 a.m., and three city engine companies were dispatched to the school at 4000 La Colina Road, said Capt. Gary Pitney.
Firefighters were able to quickly knock down the flames and control the fire, but not before it caused damage to four cars, Pitney said, adding that one vehicle sustained major damage.
No structures were threatened and no injuries were reported.
Investigators were able to quickly determine that the blaze was deliberately set, Pitney said, and are asking anyone with information to Fire Department at 805.965.5254.