The incident happened Tuesday night after the car careened down the side of a canyon near Kagel Truck Trail and Little Tujunga Canyon Road, according to California Highway Patrol.
The CHP said the car rolled down the hill about 300 feet.
The driver was able to get out, but the woman was trapped.
Christian Hernandez said it took him about 30 minutes to get up the hill. And because cellphone service was so spotty, it took nearly an hour for ambulance and police to get there.
The woman was eventually rescued and taken to the hospital in unknown condition.
The cause of the crash is under investigation.