CHATSWORTH - Hundreds of northwest San Fernando Valley residents were driven from their homes Wednesday night as the season's first serious brush fire raged across ridges and through canyons, fanned by searing Santa Ana winds.

More than 700 firefighters battled the fast-moving brush fire, one of a series that flared up in the eastern Ventura County and Santa Clarita Valley areas. Towering orange flames lit up the region and a massive cloud of smoke was pushed southward by powerful winds.

Two homes were destroyed and dozens of others were threatened as residents of Bell Canyon and Box Canyon were ordered to evacuate. Many sought refuge at Canoga Park High School and others hauled horses to safety at Pierce College.

The Ronald Reagan Freeway was closed as the 3,500 acre fire engulfed it on both the north and south sides in Chatsworth, causing massive traffic jams across the Valley.

Mayor Antonio Villaraigosa, who cut short a terrorism simulation meeting in Lake Arrowhead to meet with fire officials in Chatsworth, praised the city's response to the blaze and the cooperation with other city and county agencies.

"We have 700 personnel (fighting the fire) ... and we should have about 1,000 tomorrow, and if we need more, we'll have more than that in the morning," Villaraigosa told KCAL news from the fire line.

"The sky is bright orange, and the last time we looked, we had emergency vehicles outside the house," Margaret Douglas said as she packed up family photos and her favorite artwork before evacuating her Bell Canyon home.

One home destroyed in Box Canyon belonged to George Feo, who managed to escape as flames engulfed his house.

"It caught fire while I was inside," he said in a cell-phone conversation captured by KCAL (Channel 9) "I was loading as much as I could (in the car) and I could see the flames in the house. We got out. I'm glad we got out."

Victoria Manos, a 30-year resident of Bell Canyon who has lived through a number of evacuations, drove to the West Hills baseball field, where neighbors gathered to wait it out.

"We didn't know we only had five minutes to get out. It was just enough time to pick up my dog and my cat, which isn't that good because I usually take photographs and documents and this time I couldn't."

After the heavy growth of vegetation from last winter's near-record rainfall, authorities had warned repeatedly that the fire danger would be extremely high this summer and fall - warnings that prompted many residents to clear brush near their homes and prevent even more serious problems Wednesday, according to firefighters.

With the season's first hot Santa Ana winds, officials' predictions came true with a vengeance as brush fires flared across Ventura, Riverside and San Bernardino counties, as well as the Valley.

The Chatsworth fire - the day's most dangerous - started about 1:45 p.m. near Topanga Canyon Boulevard and the 118 Freeway and scorched hundreds of acres on its steady march over the Santa Susana Pass and hugging the county line along the canyons.

A thick plume of smoke was visible from the Los Angeles Basin and ash from the fire was falling as far away as Westlake Village.

As of late Wednesday, the fire was only 5 percent contained and officials did not yet know what had caused it.

While weather forecasters said temperatures would cool and winds would die down, fire officials were still concerned about the winds and the likelihood that they would continue today.

"We're going to be fighting this from the air and the ground, but we're going to be at the mercy of the winds," said John Mancha, a Los Angeles County fire inspector.

"It's still going to be hot and we're still going to have the winds out there."

Firefighters, aided by water-dropping helicopters, faced one dramatic moment after another as they tried to protect property and save lives.

"The winds were so bad, you could see the flames jumping," said Kim McQuestion, who has lived in the Rocky Peak area for 17 years. "My friend who lives up there and was watering his front lawn said the flames had come up to the front door. And just as he said that, a helicopter dropped water on him."

Residents who voluntarily evacuated the area gathered at Canoga Park High. Traffic quickly backed up on surface streets and other freeways as motorists struggled to find alternate routes home.

Residents of homes in Chatsworth's rugged canyons lined Topanga Canyon Boulevard and spilled into local neighborhoods, anxiously watching the flames burning across the crest of the hills.

"The challenge is that the terrain out there is all rock," Los Angeles County fire Inspector Andrew Olvera said.

One firefighter, who was struck in the back by a falling 30-pound boulder as he battled the flames, was listed in stable condition at a local hospital. He was expected to be released late Wednesday.

In southeastern Ventura County, a midday blaze of unknown origin raced over 30 acres of brush in Moorpark, closing night classes at the nearby community college. No structure losses or injuries were reported and the fire was fully contained shortly after 2 p.m., said Ventura County Fire Department spokeswoman Michele Faina.

Today should see highs in the upper 90s in the Valley, slightly lower than Wednesday, and winds should fall to about 15 mph, a National Weather Service forecaster said.

The Chatsworth fire was the first major brush fire in the San Fernando Valley this year, and it gave residents a stark reminder of the 2003 fire season, when wildfires burned through much of Southern California over a 10-day period.

Ten major wildfires burned in five counties in October and November 2003, engulfing nearly 750,000 acres, burning 3,626 homes and 1,184 outbuildings, and killing 22 people.

"It was in my backyard," Lisa Ryan of Simi Valley recalled of the 2003 fires.

"I feel horrible; all these people are displaced. They're having to watch their homes burn to the ground. I know what they're going through. This is very sad."

The fire near Moorpark College closed the college and threatened some nearby homes, but resulted in no structural damage or injuries, said Faina. That blaze broke out at Pecan Avenue.

About 200 emergency personnel and two helicopters were on scene fighting that fire.

At one point, Metrolink trains on the Ventura County line were ordered to slow to 20 mph between the Chatsworth fire and an area about one mile east of Simi Valley, a Metrolink spokeswoman said. Trains normally travel between 50 mph and 70 mph, meaning there will be delays of about 15 minutes on the line, she said.