The shooting happened around 8:00 pm in the area of 8th and J streets.
Investigators say the woman was talking to her boyfriend, who was standing outside the car, when she was shot.
She was rushed to a local hospital, where she is in critical condition.
Detectives are still working to identify the suspect and the vehicle involved in the shooting.
The motive is unknown, but officials say they believe it might be gang-related.
Anyone with information about this shooting is asked to call Detective Jose Diaz at (559) 600-8204.