Homes burned in a wildfire threatening neighborhoods in dangerously dry foothills of Southern California’s San Gabriel Mountains on Thursday, fanned by gusty Santa Ana winds that spit embers into the city below. Residents who awakened in the pre-dawn darkness to see flames approaching were ordered to evacuate.

Television images showed several structures engulfed in flames in a neighborhood abutting Angeles National Forest, just north of the San Gabriel Valley community of Glendora. Homes are nestled in canyons and among rugged ridges that made an accurate assessment difficult.

At least 125 acres of dry brush was charred in the wilderness area about 25 miles northeast of downtown Los Angeles.

Police said they questioned three persons of interest detained near Colby Trail, where the fire was believed to have started. Sheriff’s Sgt. Raymond Roth stressed that they were not suspects.

The notorious Santa Anas, linked to the spread of Southern California’s 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. The area, which has been historically dry, has been buffeted by the winds which have raised temperatures into the 80s. The Santa Anas typically begin in the fall and last through winter into spring. A wet winter reduces fire risk, but the whole state is experiencing historically dry conditions.

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 of the city of 50,000 to leave. Citrus College, located in the heart of Glendora, canceled classes for the day.

Several schools were closed. The Glendora Unified School District closed Goddard Middle School, which was being used as a fire department command post. District spokeswoman Michelle Hunter said 900 students attend the school, which is near the fire and within the evacuation area.

More than 500 firefighters were on the scene. 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.

Ash rained down on the city, said Jonathan Lambert, 31, general manager of Classic Coffee.

“We’re underneath a giant cloud of smoke,” he said. “It’s throwing quite the eerie shadow over a lot of Glendora.”

Resident Eric Black told KCAL-TV that he is preparing to evacuate, but he’s going to try to protect his home.

“We’re loading up the motorhome right now. If we need to go, we’ll go.” Black told the station. He had been using his garden hose to wet the brush around his house. “I’m going to stay as long as I can to try to protect.”

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.

(AP)