Firefighters endured intense summer heat Tuesday to rein in one of the largest wildfires (search) in Los Angeles County (search) while crews elsewhere continued fighting blazes that have blackened thousands of acres of California (search) brush and forest.

Firefighters had nearly contained a blaze about 45 miles north of Los Angeles that has burned more than 17,000 acres since it started July 12. The flames destroyed three homes and 12 outbuildings and threatened habitats of the spotted owl and California condor.

The fire was one of several burning across more than 40,000 acres of California, from eastern San Diego County to Yosemite National Park. The overall cost of fighting the four largest fires was estimated at $20 million.

Another wildfire in northern Los Angeles County near Santa Clarita was 65 percent contained after firefighters used helicopters, bulldozers and hand crews to battle the flames in 90-degree heat.

Nearly 1,600 homes have been evacuated since the fire began Saturday, ignited when a red-tailed hawk flew into a power line and its flaming body fell into brush.

Residents were allowed to return to homes in the Sand Canyon and Fair Oaks Ranch communities but were kept out of about 350 homes in Placerita Canyon.

One of the largest fires, 90 miles east of Los Angeles in Riverside County, has destroyed four mobile homes, 14 outbuildings and more than a dozen vehicles. The 3,667-acre fire was reported contained Tuesday.

That fire was started by a target shooter, who was given a citation and may have to pay costs of fighting the fire, said Jim Boano, a spokesman for the California Department of Forestry.

About 15 miles west of downtown Modesto, in central California's Stanislaus County, firefighters prepared for a difficult battle against a wildfire that flared near the San Joaquin River after burning nearly 1,600 acres.

The effort was hampered because the use of bulldozers to build fire breaks is forbidden in the San Joaquin River National Wildlife Refuge.

"The normal methods we would use to get a ring around the fire are not available to us," said county fire Deputy Chief Jim Weigand. "We'll have to use hand crews and wait for the fire to reach natural barriers."

A new fire erupted near the Los Angles suburb of Acton and rapidly spread to about 2,500 acres, carried by winds gusting to 25 mph.

More than 300 people were ordered to evacuate ahead of the flames, which destroyed a mobile home, an abandoned structure and a bridge. The fire also threatened a private animal refuge housing 1,000 dogs and other animals.

Helicopters made water drops as bulldozers, with flames licking close, carved firebreaks into the dry earth. Airplanes swooped low to paint the scrub with red swaths of fire retardant.

"It's definitely a tinderbox out here," county fire Inspector Mike McCormick said.

In Alaska, firefighters were having a difficult time battling a 484,000-acre fire on the outskirts of Fairbanks. About 150 people were told to evacuate Monday from a subdivision north of the city, but most chose to stay.

"A lot of those folks are holding out and watching it closely," said fire information officer Chris Papen.

The subdivision is separated from forest land by a fire break that is just the width of a bulldozer blade in some places.

The blaze was considered 20 percent contained. Heavy smoke continued to hamper efforts to use airplanes to douse the flames, and those conditions were not expected to change this week.

Alaska has been having one of its worst wildfire seasons in years, with 3.6 million acres already burned. However, most of the state's 107 fires are in Alaska's remote and unpopulated forests, and many are being allowed to burn.

In Yosemite National Park, a lightning-sparked wildfire that has closed a number of trails was being allowed to grow on one front but was otherwise mostly contained, park officials said. The blaze has burned across more than 3,800 acres.