The so-called Shockey Fire started just after noon on Sunday in Campo, about 65 miles east of San Diego. The 2,000-acre blaze has destroyed at least 20 homes, damaged 10 and burned 15 outbuildings. The fire was only 10 percent contained.
Cal Fire Capt. Mike Mohler said the hot and windy weather was contributing to the fire's growth. Highs on Monday were expected to be slightly cooler, but windy conditions were expected to persist.
Officials said 80 homes are still threatened, and those families have been forced to evacuate. An evacuation center was set up at a high school in the nearby community of Pine Valley.
More than 300 firefighters, 57 fire engines, nine fire crews, six air tankers, six helicopters, five bulldozers and nine water tenders were assigned to the fire, Mohler said. There were also roughly two dozen sheriff's deputies assisting firefighters, said San Diego County sheriff's spokeswoman Jan Caldwell.
There were no immediate reports of injury. The cause of the fire remains under investigation.
City News Service contributed to this report.