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Los Angeles, California (CNN) -- With fire season under way, hundreds of firefighters -- backed up by more than a dozen aircraft -- are battling three wildfires in southern California.
The latest -- known as the Crown Fire -- has ignited more than 13,000 acres, fire officials said. The other two have blackened more than 17,660 acres.
Gov. Arnold Schwarzenegger said the situation in southern California has changed dramatically as the weather shifted.
"We were very fortunate not to have fires for some time, because the air was cool and we didn't have the experience of dry weather and all of these winds and so on, but all of a sudden the fire season kicked in," he said at a late afternoon news conference, surrounded by a battery of firefighting officials.
"But we are ready," the governor added. "There's great coordination going on, and we have resources distributed all over the state. The governor spoke on his birthday, as he turned 63.
The Crown fire represents one of the biggest challenges.
About 1,370 firefighters and 250 fire engines were at the scene of the blaze on Friday. Authorities say it's about 20 percent contained.
The Los Angelese County Sheriff's Department said mandatory evacuation orders from overnight had been lifted, but a voluntary evacuation remained in effect. Already, some 300 homes have been evacuated.
Residents should be ready to evacuate at any time and follow instructions of deputies, the department said. Areas affected included some parts of Leona Valley, Ritter Ranch, Anaverde and Palmdale in northern Los Angeles County.
The priority Friday, said Michael Bryant, incident commander for the Los Angeles County Fire Department, is preventing the Crown Fire from destroying power lines that provide electricity throughout southern California. The lines are very near the fire.
The Los Angeles Department of Water and Power has asked residents near the fire to limit their power usage, though no fire-related outages have been reported.
Some 2,000 buildings in the area are threatened by the fire.
So far, three single-wide trailer homes and single-family residence have been destroyed, as well as two detached garages, an outbuilding, a barn and one other structure that fire officials weren't able to identify. No new structures were reported lost so far Friday.
Working against fire officials in Los Angeles County is the weather: Friday was shaping up to be the hottest day this week, with humidity in the low teens. Winds were expected to pick up by afternoon.
"That's creating a little bit of a challenge, and obviously causing a bit more fire spread," Matt Levesque, an official with the L.A. County Fire Department, said about the high temperatures and windy conditions.
The cause of the Crown Fire is under investigation.
Two more wildfires hit southern California this week: the Bull Fire, southeast of the town of Tehachapi, and the West Fire, north of Tehachapi in the Sequoia National Forest.
The Bull fire was 65 percent contained by late Friday and has burned 16,460 acres, authorities said. It has destroyed eight homes and six outbuildings, but no evacuations have been ordered.
Crews worked Friday on completing fire lines along the north, east and south sides of fire. They crossed the Kern River on rafts to work on lines on the fire's western flank Saturday.
Forestry personnel are working alongside firefighters to ensure that natural and cultural resources are protected during fire fighting operations, officials said.
Meanwhile, the West Fire has destroyed 30 structures, mostly homes. Cooler temperatures and calmer winds made firefighting efforts a little easier but officials said early Friday no part of the fire had been contained. It has burned more than 1,200 acres in Kern County so far.
Gov. Schwarzenegger has declared a state of emergency for Kern County. Evacuation centers have been set up at schools.
Authorities warned residents to keep their cars and house windows closed to prevent smoke inhalation, said spokeswoman Michelle Puckett of the U.S. Bureau of Land Management.
Kern County is approximately 130 miles north of Los Angeles.