A snow plow and car collided on the Pomona (60) Freeway in Jurupa Valley Monday amid a downpour, partially blocking westbound lanes.
The crash happened about 10:40 a.m. just east of Country Village Road, according to the California Highway Patrol.
The circumstances behind the impact were not immediately clear, but according to the agency, the two vehicles left the No. 3 and 4 lanes obstructed.
Heavy rain was moving through the area at the time, and that segment of the 60 is known for standing water.
A SigAlert was issued at 10:43 a.m. as traffic began to back up for several miles in the vicinity of the crash.
It was unclear where the snow plow was headed.
The scene was expected to be clear by 11:30 a.m., according to the CHP.