A vehicle collision near the Cuesta Grade is causing a traffic backup on Highway 101 Northbound, between San Luis Obispo and Atascadero.
The California Highway Patrol said a car collided with a semi-truck and rolled over, trapping a person inside.
Officers did not have an update on the condition of the people involved in the crash but said at least one lane of the highway was open while they were on the scene.
All lanes were reopened shortly after 8 p.m. but traffic is still slow through the areas and drivers are urged to drive with caution.
