Wind-whipped flames raged overnight in the steep, rugged mountains of the Santa Clarita Valley, charring more than 33,000 acres and threatening thousands of homes.
The Sand fire, named for Sand Canyon, continued to burn Monday in the hills toward Acton, prompting the Los Angeles County Sheriff's Department to order the evacuation of at least 10,000 homes.
"This is a big animal," said Mike Wakoski, a spokesman for the multiagency wildfire effort. "Containment of the fire is going to be slow."
A landscape of desiccated fuel has created explosive conditions for a fire averaging 10,000 football fields a day, Wakoski said.
A shift in the weather was not likely to help firefighters, although it wouldn't hinder them either, said National Weather Service meteorologist Andrew Rorke.
Weakening winds, an increase in humidity and a slight drop in temperatures were expected Monday, Rorke said, while the slight chance of thunderstorms loomed over Southern California.
When the massive blaze erupted Friday along the 14 Freeway at Sand Canyon, 30- to 50-mph winds fanned the flames on hillsides carpeted with tinder-like chaparral, pushing them into the Angeles National Forest.
Decades without a major fire and years of drought left the valley primed for a fast-moving fire that was fueled by excessive heat, low humidity and extreme dry fuels that have not burned for several decades, officials said.
The fire ripped through the hills "like a freight train" on Saturday in some areas that have not burned in some 60 years, said John Tripp, a Los Angeles County deputy fire chief.
"We've never seen a fire come into Sand Canyon like that," Tripp said. "All the experience we've had with fires is out the window."
Earlier this season, Tripp said, blazes in Calabasas, Duarte and Stevenson Ranch, which would have likely claimed 20 to 50 acres in a normal year, have spread exponentially, burning thousands of acres. Tripp said he can't help but worry about what the remainder of the season will bring.
"We are in July," he said.
"We've never had four major fires within six weeks in June and July."
Mandatory evacuations were still in place for about 1,500 residents in parts of Sand and Placerita canyons, as well as for others along Little Tujunga Canyon Road.
As water-dropping helicopters worked overnight, the firefight got a significant boost Monday: the number of firefighters increased from 1,600 to nearly 3,000, according to the U.S. Forest Service. The fire remains only 10 percent contained.
"It's burning so quickly and so rapidly that our firefighters are getting in and doing a lot of great work, but to get in and do some of that stuff safely is very difficult," said Justin Correll, an engine fire captain in San Bernardino National Forest.
One fatality has been reported. Firefighters found a man's body inside a burned car parked in a driveway.
At least 18 structures have been destroyed and one damaged in the Angeles National Forest near the Bear Divide and Sand Canyon areas, according to the Los Angeles County Fire Department.
Bruce Sanborn and Suzi Fox learned they had lost the house they shared on Little Tujunga Canyon Road after seeing its charred shell on the Saturday news.
The couple had evacuated to Hart High School in Santa Clarita the day before.
During a trip to a store, Sanborn saw images of their burned property flash across a television.
"I was just sitting there stunned," Sanborn, 55, said.
"Up to that point, in the back of my mind, we were still going home."
A woman who learned of the couple's plight contacted them on Facebook and offered up her home while she was away on vacation.
Support has also been offered to two firefighters assigned to the Sand fire whose homes at a forest service facility were destroyed.
One of the men had lost a home in the 2009 Station fire.
The South Coast Air Quality Management District warned residents in smoke-filled areas to avoid vigorous outdoor and indoor activities as the air quality approached an unhealthy level.
At least one drone was spotted over the fire near the Bear Divide area, about 2,000 feet above Lake View Terrace, according to the U.S. Forest Service.
The sighting of a drone over a wildfire typically prompts officials to ground aircraft for 30 minutes. "If you fly, we can't," said Angeles National Forest Fire Chief Robert Garcia.
The Forest Service said that those caught flying private aircraft or drones could face criminal charges.
Los Angeles County Supervisor Michael Antonovich said Monday that the county currently leases a water-dropping aircraft known as a "super scooper" from Canada which is set to arrive next month. Antonovich said the county hopes to renegotiate that contract and review its financing plan for future fires.
"We're now finding that fire season is not just a particular time of the year," he said.
"It's basically all year."
Drew and Chris Pease lost their home on Oak Springs Canyon Road when flames swept through the area over the weekend.
The couple had lived on their 13-acre property for nearly 17 years.
When she heard about mandatory evacuations Saturday, Chris packed her three pygmy goats into a carrier.
A friend came and helped her hook up the horse trailer, but she was unable to get her horse, Abby, inside, no matter how hard she tried.
"It was the most frightening thing," Chris Pease, 66, said.
"The flames were leaping up in some areas 50 feet in the air 100 feet in the air.
It was coming running down the hill, just a big, red glow, almost like lava."
A firefighter urged her to leave the area immediately.
He said they would do their best to save the animals.
"But I looked on his face and I saw it," Chris said. "I knew."
Chris left behind the birds, goats and Abby.
Animal rescuers later tried to get Abby on her feet, even attempted lifting her with a tractor, Pease said.
The horse had no broken bones, but did not want to get up.
A veterinarian called to say he could give Abby fluids. "What if you can't get her up?" Pease asked. "She's going to lay there and burn to death? I can't bear that." Pease then made a painful decision. She requested that Abby be put down.
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