A rock slide partially blocked Highway 74 between Mountain Center and Valle Vista Monday.
The slide was reported about 11:20 a.m. on the westbound side of the two-lane corridor, roughly three miles west of Mountain Center, according to the California Highway Patrol.
No vehicles were damaged.
CHP officers summoned a Caltrans crew to clear the obstruction, but as of 12:45 p.m., the crew had not completed its work.
There was no lane closure in place, but motorists were having to avoid the rocks, according to reports from the scene.
It was unknown what might have triggered the slide.