Fire crews on Sunday continued to battle a fast-moving brush fire in San Diego County.
The blaze, which fire officials warned was burning at a "dangerous rate of speed," scorched 4,000 acres in the Japatul Valley area, and prompted evacuations for some residents near the remote community of Alpine in the Cleveland National Forest.
A strike team consisting of five fire engines and two battalion chiefs was sent to assist Cleveland National Forest and CAL FIRE crews overnight Saturday.
By Sunday morning, it had destroyed at least 10 structures and was 0% contained.
CAL FIRE said nearly 12,500 firefighters were battling 22 major fires in the state. Despite the heat, firefighters were able to contain two major fires in coastal Monterey County.
California has seen 900 wildfires since Aug. 15, many of them started by an intense series of thousands of lightning strikes. The blazes have burned more than 1.5 million acres. There have been eight fire deaths and nearly 3,300 structures destroyed.
The heat wave was expected to spread triple-digit temperatures over much of California through Monday. Officials urged people to conserve electricity to ease the strain on the state's power grid.
The hot spell and accompanying low humidity and gusty winds out of the east prompted the National Weather Service to issue a "Red Flag'' wildfire warning for the inland valleys and mountains, effective until 6 p.m. Sunday. The alert signifies a likelihood of critical combustion hazards that can lead to "extreme fire behavior.''
The Associated Press and City News Service contributed to this report.