The crash happened Monday afternoon when a driver tried to pass on the right shoulder off Gilman Springs Road, according to the California Highway Patrol.
Authorities say that car ran out of room and hit a guardrail, causing it to swerve back into traffic and triggering a chain-reaction car with three other cars.
The driver of the passing vehicle died at the scene, and a passenger was taken to the hospital with major injuries.
One of the other cars involved was forced off the road and into a field, where it burst into flames and caused a small brush fire. One adult and two children in that car died.
The ages and identities of the children or other individuals have not been released.
Authorities initially thought only four people died, but they later found two other people dead while combing through the wreckage.