Officials with the California Highway Patrol say the crash happened around 5:20 pm in the area of Del Rey and Herndon avenues.
Investigators say a woman believed to be in her 80s was walking across the street to her mailbox when she was hit by a vehicle.
The woman was flown by helicopter to a local hospital in critical condition.
The driver pulled over after the crash and has been cooperating with officers.
Officers say drugs or alcohol were not involved in the crash.