A tractor-trailer that struck a tree amid heavy rain Monday blocked one side of a two-lane corridor just east of Lake Mathews.
The crash was reported shortly before 10 a.m. on Gavilan Road, near Cajalco Road, according to the California Highway Patrol.
The big rig hit the tree and came to a stop on the southbound side, making it impassable, according to the CHP.
As of 10:45 a.m., crews were working to clear the roadway.