Huntington Park Police Department officers were called at 9:40 p.m. Monday to the 3900 block of East 60th Street, between Carmelita and Corona avenues, where they found the woman fatally shot inside the vehicle, according to the Los Angeles County Sheriff's Department.
The woman was pronounced dead at the scene. Her identity was not immediately released.
Footage showed detectives investigating a Ford pickup truck that had a bullet hole in the windshield.
A second gunshot victim - a man - was found at a nearby liquor store in the 4000 block of Slauson Avenue. His condition was not immediately available.
"Investigators learned the male victim was with the female victim when the shooting occurred and ran from the scene immediately following the shooting," according to the Sheriff's Department.
LASD detectives were assisting Huntington Park police with the homicide probe, the Sheriff's Department said.
No description of a suspect was available.
Anyone with information about these shootings was asked to call the Sheriff's Department's Homicide Bureau at 323-890-5500. Those who wish to remain anonymous can call Crime Stoppers at 800-222-8477 or visit lacrimestoppers.org.