A wildfire burned out of control near homes in the dangerously dry foothills of the San Gabriel Mountains early Thursday, fanned by gusty Santa Ana winds that spit embers into neighborhoods in the city below, igniting trees. Evacuations were ordered for houses at the edge of the fire.
The blaze charred at least 30 acres above a neighborhood abutting a canyon of Angeles National Forest, just north of the San Gabriel Valley community of Glendora. The wilderness area is about 25 miles northeast of downtown Los Angeles.
The notorious Santa Anas, linked to the spread of Southern Californians worst wildfires, picked up at daybreak. The extremely dry Santa Anas blow downslope and can push fires out of the mountains and into communities below.
TV news helicopters spotted embers igniting palm trees in residential yards as firefighters with hoses beat back flames lapping at the edges of homes.
Glendora police said officers were going door to door ordering residents to leave. Citrus College, located in the heart of Glendora, canceled classes for the day.
The Los Angeles County Fire Department deployed seven engines and three helicopters to the fire, which was reported around 5:50 a.m. (PST) and was growing rapidly. Officials added to the firefighting aircraft with a water-dropping Super Scooper plane.
The fire erupted abruptly, said Jonathan Lambert, general manager of Classic Coffee in Glendora.
"All of a sudden a customer came in, `Have you seen the fire?' `No, we haven't.' We went outside and it's been moving incredibly quickly down that hill," Lambert told KNBC-TV.
The last catastrophic fire in the San Gabriel Mountains broke out in 2009 and burned for months. The flames blackened 250 square miles, killed two firefighters and destroyed 209 structures, including 89 homes.
California is in a historically dry era and winter has brought no relief.
Red flag warnings for critical fire weather conditions were posted from Santa Barbara County south through Los Angeles to the U.S.-Mexico border, along the spine of the Sierra Nevada, and in areas east and north of San Francisco Bay.
Fires that struck windy areas of the state earlier in the week were quickly quashed by large deployments of firefighters, aircraft and other equipment before the flames could be stoked by gusts into major conflagrations.
Large parts of Southern California below mountain passes, canyons and foothills have been buffeted all week by the region's notorious Santa Ana winds.
Spawned by surface high pressure over the interior of the West, the Santa Anas form as the cold air flows toward Southern California, then speeds up and warms as it descends in a rush toward the coast. Some of the most extreme gusts reported by the National Weather Service topped 70 mph.
These offshore winds also raise temperatures to summerlike levels. Many areas have enjoyed temperatures well into the 80s.
California is also under the influence of a persistent upper-level ridge of high pressure anchored off its north coast that has also kept the region generally warm, dry and clear.