BYRON (CBS SF) — At least one person has been killed in a multi-vehicle crash on winding and heavily-traveled Vasco Road in eastern Contra Costa County, authorities said.

The East Contra Costa County Fire Protection District the crash involved three vehicles including a big rig that ended up on its side.

The California Highway Patrol said Vasco Road was shut down entirely between Camino Diablo and Dalton following the crash.

Motorists were urged to avoid the area and use Interstate 680 to get between eastern Contra Costa and Alameda counties.

Vasco road was opened in both directions around 6:21 p.m., according to the CHP.

There was no immediate word on the cause of the crash.