CHP units responded to reports of a single-vehicle crash with a center divide on state Highway 4 near McEwen Road west of Martinez at around 11:55 p.m., CHP Officer Ralf Caggiano said.
A patrol car from the Pinole Police Department was traveling west with a person in custody onboard when for unknown reasons it crashed into the center divide, Caggiano said.
No one appears to have been injured, Caggiano said.
The crash remains under investigation.