Jung Ja Lee, 69, of Laguna Woods, was found not breathing in her car parked at a McDonald's restaurant.
The fire department was called to the scene. Lee was being transported to St. John's Regional Medical Center when police arrived.
Lee later died at the hospital, and the cause of death remains unknown. The Oxnard Police Department classified Lee's death as suspicious and is conducting an investigation.
Anyone with information regarding Lee's death is asked to call Oxnard Police Department at (805) 385-7600.