A car flipped over on the Ramona Expressway just east of Nuevo Monday, injuring one of the occupants.
The rollover crash was reported at 11:25 a.m. on the eastbound side of the expressway, near Bridge Street, according to the California Highway Patrol.
The agency said the sedan overturned for unknown reasons, rolling at least once before coming to rest on its roof.
Good Samaritans stopped and assisted the two occupants in escaping the wreckage, according to officials at the scene.
Riverside County Fire Department crews arrived minutes later and assessed the victims, one of whom suffered unspecified injuries. The other person was not hurt.
It was not immediately known whether the injured party required hospitalization.
The CHP shut down the eastbound side of the corridor to conduct a preliminary investigation and clear the wreckage.
The expressway was expected to be fully reopened by 1 p.m.