A multi-vehicle collision has all but the HOV lane stopped on the eastbound Interstate 210 freeway at Grand Avenue.
Two vehicles collided in the No. 1 and 2 lanes of the freeway, according to California Highway Patrol traffic logs.
The crash was reported around 4:33 p.m.
At 4:41 p.m, all traffic lanes had been stopped, but the HOV lane was reopened at 4:51 p.m., with the No 1 and 2 lanes reopened at 4:58 p.m. Vehicles stopped in traffic are reportedly exiting down the Grand Avenue on ramp to escape the gridlock, the CHP said.
The extent of injuries was unclear.