Investigators say the victim's 2002 Jeep Wrangler slammed into the trailer of a big rig near Walnut Street and Wilmington Avenue at 10:55 p.m.
Responding deputies arrived to find the jeep's roof sheared off.
For an unknown reason, the driver of the jeep ran a red light and collided into the trailer of a big rig.
The woman driving the jeep was transported to Harbor General, where she succumbed to her injuries.
The driver of the big rig was not injured.
Investigators were working to determine whether speed, alcohol or cellphone activity played a role in the fatal crash.