Plummer was apparently walking on Highway 24 just east of Pleasant Hill Road following an accident when she was struck shortly before 3:30 a.m., according to the California Highway Patrol.
The CHP said the chain of accidents started around 3:15 a.m. when a red Nissan Sentra veered left into the center divider and stopped in the second lane from the right. The driver of that vehicle got out of the car and waited in the center divider area.
A short time later, a white Ford Focus in which Plummer was riding as a passenger struck the Sentra. The driver and Plummer exited the vehicle and went to the center divider.
Plummer apparently attempted to return to her car a short time later though and was struck by a white Chevrolet Cavalier while she was in the roadway.
The driver and passenger of the Cavalier stayed at the scene, and CHP officials say alcohol and drugs do not appear to have been a factor in this collision.
The crash closed the three left lanes of eastbound Highway 24 for approximately three hours this morning.
The CHP recommends people involved in a collision to stay in their car if an extremely safe place to wait for authorities to arrive cannot be found.
