State troopers responded to the scene, I-5 at Highway 599, at about 4:30 p.m. after receiving a report of a serious crash involving multiple vehicles.
The woman was found dead at the scene.
An investigation found that the 71-year-old woman was heading north in the slow lane of northbound I-5 in a 1996 Volkswagen GTI when she struck a 1992 Ford pickup traveling in the next lane in the same direction.
The woman then over-corrected to the left, crossing all northbound lanes of the freeway. Her car rolled over, striking a 2010 Ford Mustang in the southbound lanes of Highway 599 HOV bypass to southbound I-5.
The victim was ejected and her car came to rest in a lane of the HOV bypass.
A fourth vehicle was struck by flying debris from the crashed Volkwagen.
The crash remains under investigation.
The woman's identity is being withheld pending notification of her next of kin.