Two Los Angeles County firefighters were killed Sunday when their vehicle rolled down a mountain side amid the intense flames of a wildfire that threatened 12,000 homes. Gov. Arnold Schwarzenegger urged those in the fire's path to get out as the blazes rained ash on cars as far away as downtown Los Angeles, spreading in all directions in dry conditions. Firefighters fixed their attention on the blaze's fast-moving eastern side where flames lapped at the foot of the vital communications and astronomy center of Mount Wilson, and on the northwestern front, where the two firefighters were killed on Mount Gleason near the city of Acton. "We ask for your understanding, for your patience as we move through this difficult time, and please, prayers for the families of our two brothers that we lost," county Deputy Fire Chief Mike Bryant said through tears at a Sunday night press conference. Bryant said the men's families have been notified. He did not release their identities or give a cause for the crash, and officials at the press conference would take no questions on the deaths. Television helicopter video on Sunday night showed an upside-down vehicle on the mountain side. "Our hearts are heavy as we are tragically reminded of the sacrifices our firefighters and their families make daily to keep us safe," Schwarzenegger said in a statement. The blaze was only about 5 percent contained and had scorched 71 square miles in the Angeles National Forest. Mandatory evacuations were in effect for neighborhoods in Glendale, Pasadena and other cities and towns north of Los Angeles. Officials said air quality in parts of the foothills bordered on hazardous. The fire, which broke out Wednesday afternoon, was the largest of many burning around California, including a new blaze in Placer County northeast of Sacramento that destroyed 60 structures, many of them homes. The Southern California fire was expected during the night Sunday to reach the top of Mount Wilson, where 22 television stations, many radio stations and cell phone providers have their transmitters, said U.S. Forest Service Capt. Mike Dietrich. Firefighters were pulled from the top of the mountain after clearing brush and spraying retardant on antennas because it was too dangerous for them to remain. "We've done all the preparation we can," county fire spokesman Mark Savage said. Television stations said if the antennas burn broadcast signals will be affected but satellite and cable transmissions will not be. Two giant telescopes and several multimillion-dollar university programs are housed in the century-old Mount Wilson Observatory. The complex of buildings is both a historic landmark and a thriving modern center for astronomy. At least 18 homes were destroyed in the fire and firefighters expected to find many more, authorities said. While thousands have fled, two people who tried to ride out the firestorm in a backyard hot tub were burned. The pair in Big Tujunga Canyon, on the southwestern edge of the fire, "completely underestimated the fire" and the hot tub provided "no protection whatsoever," Sheriff's spokesman Steve Whitmore said Sunday. The pair made their way to firefighters and were airlifted out by a sheriff's rescue helicopter. They received adequate notification to evacuate from deputies but decided to stay, Whitmore said. Whitmore described their condition as "critical" but fire officials said one of the two was treated and released and the other remained hospitalized in stable condition. A third person was burned Saturday in an evacuation area along Highway 2 near Mount Wilson, officials said. Details of that injury were not immediately known. "There were people that did not listen, and there were three people that got burned and got critically injured because they did not listen," Schwarzenegger said at a news conference at the fire command post. For the third straight day, humidity was very low and temperatures were expected in the high 90s. Nearly 3,000 firefighters were battling the blaze. Mandatory evacuations were also in effect for neighborhoods in Altadena and for the communities of Acton, La Canada Flintridge, La Crescenta and Big Tujunga Canyon. There was some progress Sunday, as a small number of La Canada Flintridge residents living west of the Arroyo Seco were told they could go back to their homes. But more evacuations were ordered in Acton in the Antelope Valley, and school districts in La Canada Flintridge and Glendale announced that classes were canceled Monday because of the fire. Fixed-wing aircraft and a DC-10 jumbo jet were dropping water and flame retardant on the fire. At the fire command post, Schwarzenegger praised firefighters for successfully protecting subdivisions in the foothills. Rob Driscoll and his wife, Beth Halaas, said they lost their house in Big Tujunga Canyon. By Sunday they were desperate for more information and came to the command post to get answers. "Our neighbors sent us photos of all the other houses that are lost," Halaas said, her voice breaking as her young son nestled his sunburned face in her arms. "We've heard as many as 30 houses burned." At least 12 evacuation centers were set up at schools and community centers in the area. The center at Crescenta Valley High School filled up, but by Sunday afternoon fewer than two dozen people remained. Residents trickled in to get information and snacks. Debbie and Mercer Barrows said their house was saved but they lost their scenic view of a hillside to the flames. "That'll grow back," said Mercer Barrows, a TV producer. To the north, at least 60 structures - many of them homes - were destroyed in a fast-moving fire that broke out Sunday afternoon in the Sierra foothills town of Auburn northeast of Sacramento and the governor declared a state of emergency in the area. The fire had consumed 275 acres amid high winds and was 50 percent contained Sunday night, CalFire spokesman Daniel Berlant. Berlant said it was not clear how many of the burned structures were homes and it was likely to remain uncertain until daylight. About 30 people waited anxiously for news at an evacuation center in the Rock Creek Elementary School. Pam and Stephen Incerty did not know the fate of their home on a beautiful 5-acre parcel in the rolling hills covered with trees. Stephen Incerty wondered what the land looks like now after fire has ripped through it. "If there's nothing there when we get back, we won't rebuild," he said. "There'd be no trees, just dirt." In the state's coastal midsection, all evacuation orders were lifted Sunday after a 10-square-mile fire burned near the Monterey County town of Soledad. The blaze, 80 percent contained, was started by agricultural fireworks used to scare animals away from crops. The fire destroyed one home. In Mariposa County, a nearly 7-square-mile fire burned in Yosemite National Park. The blaze was 50 percent contained Sunday, said park spokeswoman Vickie Mates. Two people sustained minor injuries, she said. Park officials closed a campground and a portion of Highway 120, anticipating that the fire would spread north toward Tioga Road, the highest elevation route through the Sierra. About 50 homes in the towns of El Portal and Foresta were under evacuation orders and roads in the area will remain closed through Monday, Mates said.