Neighbors knew something was wrong when they heard a splash and cries for help, just before 3:00 a.m. Tuesday.
Police arrived to find a 19-year-old by the side of a swimming pool with the car he had been driving submerged in the deep end.
The driver's mother spoke to ABC7 News about what happened.
"He was taking his friend home and it was too late. He fell asleep. He was too tired," said Isabel Zavala, the teen driver's mother.
PHOTOS: Driver plunges car into pool at home in Santa Clara
"Officers on the scene ran him through field sobriety tests, checked him out completely and determined he was not under the influence of drugs or alcohol. It appears he fell asleep," said Dan Moreno, with the Santa Clara Police Department.
The teen was not willing to talk to us on camera, but he told a neighbor how he escaped from the car.
"He said that he'd gotten out the back door. The back door had opened, and he was able to get out through the back door," said Elaine Regan, a neighbor.
It took two tow truck operators to get the car out of the pool.
"Trying to get the vehicle without damaging the pool, so basically the lift, the lift was the most challenging part of the situation," one tow operator told ABC7 News.