State fire officials say the wildfire near Julian had surged by sunset Monday to more than seven square miles.
Campgrounds, buildings and the few occupied mountain cabins in the area have been evacuated. Lodges at the Al Bahr Shrine Camp at a Sierra Club camp were destroyed. At least six other structures were damaged or destroyed, but it was not immediately clear what they were.
The highway through the Mount Laguna Recreational Area was shut down from Interstate-Eight and state Route 79.
Firefighters with help from water-dropping aircraft had it 15-percent contained.