The western flank of the deadly wildfire north of Los Angeles was under control Saturday, sparing foothill communities further threat as it burned east into a large wilderness area.
Investigators, meanwhile, were working to find the arsonist responsible for the huge wildfire that has killed two firefighters and burned nearly 242 square miles, or 154,655 acres, of the Angeles National Forest.
The fire's origin near Angeles Crest Highway remained cordoned off as authorities sought more clues in the case, but they were hesitant to release any findings to the media.
"Arsonists are not stupid. They can read," said U.S. Forest Service Cmdr. Rita Wears, who supervises federal agents investigating the fire. "I have to be very careful."
Los Angeles County firefighters Tedmund Hall and Arnaldo Quinones were killed Aug. 30 while seeking an escape route for their inmate fire crew after flames overran their camp on Mount Gleason.
Sheriff's detectives opened a homicide investigation after the fire was ruled arson earlier this week, and Gov. Arnold Schwarzenegger has offered $100,000 for information leading to the arrest and conviction of the culprit.
49 percent contained
The fire, one of the largest in Southern California history, was 49 percent contained by early Saturday afternoon after crews built protective lines on the northwestern flank near Santa Clarita, according to Forest Service spokeswoman Jan Ulrich.
Firefighters were trying to slow the fire's eastern movement into the San Gabriel Wilderness and secure the southeastern flank north of Monrovia and other foothill communities. No homes were threatened, Ulrich said.
Mount Wilson — which holds a historic observatory and at least 20 television transmission towers, radio and cell phone antennas — appeared well-protected after flames came dangerously close earlier this week.
"They say Mount Wilson is prepped better than it's been in about the last 100 years," Forest Service spokeswoman Barbara Rebisky said. "That's looking real good."
Crews with local utilities were preparing to move into the fire zone to repair or replace more than 1,000 damaged or downed power lines, Rebisky said.
The weekend weather forecast called for cooler temperatures and slightly higher humidity that could help firefighters further surround the blaze, which has cost fire agencies $37 million to fight.
At least a dozen investigators were working to analyze clues found at a charred hillside, including incendiary material reported to have been found there. Officials said the fire was arson but were still investigating who started it and how.
"We are in the early stages, just beginning to put things together," said Los Angeles County sheriff's Lt. Liam Gallagher, who is heading the homicide investigation. "Firefighters losing their lives in the line of duty is an added incentive, but we work every case to the fullest."
Near a large shade tree where crews get their twice daily briefings, firefighters set up a makeshift memorial to the two dead firefighters. They helped save about 60 members of an inmate fire crew last Sunday as flames approached their camp when they set a backfire that allowed the group to get to safety. The pair died when their truck plunged 800 feet down a steep mountain road as they sought an escape route.
Most wildfires are caused by human activity, and government statistics show that people were faulted for 5,208 wildfires in Southern California in 2008, the highest number since at least 2001. Between 2006 and 2008, Southern California was the only region of the country to see a significant jump in the number of wildfires blamed on people.
Still, very few of the forest fires lead to criminal or civil cases. The U.S. Forest Service recorded nearly 400 arson wildfires since 2005, records show.
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