Firefighters battle a wall of flames today near the mountain community of Lake Arrowhead, Calif. Officials ordered the evacuation of 35,000 residents in around the area as the wildfire roared toward them. Associated Press

Crews battling some of the most destructive and deadly wildfires in California history are so exhausted they are being pulled off fire lines, even if it means more homes will be destroyed, a Forest Service fire chief said today as a pair of blazes threatened to merge in San Diego County.

At least 17 deaths were blamed on the fires, 15 in Southern California and two in Mexico, as separate blazes were scattered along an arc from the suburbs northwest of Los Angeles to Ensenada, Mexico, about 60 miles south of the border. At least 1,552 homes had been destroyed in California.

Firefighters beat back flames that had threatened hundreds of homes in northwest Los Angeles, but conditions were more critical to the south in San Diego County, where the Cedar and Paradise fires were separated by only two miles and threatening to join.

"There’s blocks of homes that are going to burn to the ground this afternoon, in my opinion," said Rich Hawkins, a Forest Service fire chief. "My objective is to make sure there’s nobody in them."

Hawkins said some firefighters were being taken off the lines this morning.

"They’re so fatigued that despite the fact the fire perimeter might become much larger, we’re not willing to let the firefighters continue any further," Hawkins said of firefighters fighting the Cedar and Paradise fires. "They are too fatigued from three days of battle."

Hawkins said that lunches intended for firefighters yesterday weren’t delivered until today and there was a shortage of diesel fuel in some cases.

"It’s like war. This whole fire has been a war so far," Hawkins said.

The mountain community of Julian in San Diego County was being evacuated.

More than 521,929 acres of brush, forest and homes — or about 815 square miles, roughly three-quarters the total area of Rhode Island — had burned in California.

Crews battling the Simi Valley fire in the Santa Susana Mountains, which separate the northwest corner of Los Angeles from Simi Valley in neighboring Ventura County, had feared they could lose hundreds of homes in the Chatsworth section.

"They saved every one of them," said Bill Peters, a spokesman for the California Department of Forestry.

Firefighters went driveway to driveway through the night in the Chatsworth area, which extends up the Santa Susana slopes from the city’s San Fernando Valley, and turned back the flames before dawn, Peters said.

The fire teams were aided by reinforcements who arrived yesterday and by calmer weather that included increased humidity, lower temperatures and a break from the Santa Ana wind that had gusted up to 70 mph earlier in the week. The hot, dry Santa Ana blows from the high desert down to the sea at this time of year.

More than 10,000 firefighters were battling the flames. More resources were on the way from Arizona and Nevada, which each volunteered the use of 50 fire trucks, and Nevada also was sending three helicopters.

Crews east of Los Angeles lost 20 buildings during the night in the Strawberry Peak section of the San Bernardino National Forest. They couldn’t immediately say if the structures, near Lake Arrowhead, were homes or outbuildings.

The Strawberry Peak area was hit by a combination of two fires that had merged into one during the weekend. One, the Old Fire, had destroyed at least 450 homes and been blamed for two deaths.

Lake Arrowhead, at an elevation of 5,100 feet, was particularly vulnerable because a beetle infestation has devastated trees in the area.

In Mexico, meanwhile, firefighters had brought under control all but two of the 30 wildfires that started during the weekend, and hundreds of people evacuated near Ensenada had been allowed to return home, an emergency official said today. Two people died Sunday when they were trapped in their burning home, one of about 15 Ensenada houses destroyed by the flames.

Two of the fires in Mexico had spread across the border from California and one, near Tecate, was still burning today, emergency official Raymundo Noriega said.

Some of the California fires were believed started by arsonists. Investigators sought two men who were seen throwing flaming objects from a van in the area of the Old Fire.

Yesterday, President Bush declared the region a disaster area, opening the door for aid to residents and businesses in Los Angeles, San Bernardino, San Diego and Ventura counties.

Scores of people have been injured by this week’s fires. Two people at the University of California-San Diego, Medical Center were reported in serious to critical condition with burns over more than 55 percent of their bodies.