The crash happened just before 2:30 a.m. at Crenshaw and Washington boulevards. According to one witness, the woman stepped further when she was crossing the street, got on her knees and tucked her head down before she was hit.
The dark-colored, four-door sedan was traveling southbound on Crenshaw Boulevard and did not stop after the crash.
Authorities said an ambulance crew in the area also witnessed the crash, which is being looked into as a possible suicide.
A detailed description of the driver and car were not released.