The incident happened at Downey Avenue just after 11 p.m. Sunday and resulted in the temporary closure of all westbound lanes, according to the California Highway Patrol.
When officials arrived at the scene, one person was pronounced dead.
Witnesses reported the victim was hit by a car while changing their tire on the side of the freeway, but police were still trying to confirm that.
Authorities are investigating the crash as a hit-and-run. A description of the vehicle that was involved was not available.
Anyone with information is urged to call the CHP.