Just after 4:30 p.m. a car rolled over on northbound Highway 101 near the Highway 33 off-ramp.
California Highway Patrol said the car appears to have flipped a few times and landed on its side.
Ventura County fire officials on scene reported one person was trapped and had to be extricated from the car.
Medics treated people involved for major injuries. The cause of the crash is under investigation.