LOS ANGELES - The entire western edge of the massive wildfire burning north of Los Angeles was under control Saturday, but the arson-caused blaze continued to move unchecked into wilderness to the east, officials said.
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. It was 49 percent contained. At least 76 homes and dozens of other structures have been destroyed.
Gov. Arnold Schwarzenegger offered a $100,000 reward for information leading to the arrest and conviction of the culprit.
The risk to homes was significantly reduced as hand crews held the fire line to the north, south and west, said U.S. Forest Service spokeswoman Michelle Caldwell. Aerial water drops were expected to resume Saturday to slow the fire's eastern movement into the rural San Gabriel Wilderness.
Overnight, firefighters built six miles of new lines on the northwestern flank of the blaze near Santa Clarita, according to Forest Service spokeswoman Barbara Rebisky.
A historic observatory and TV, radio and other antennas on Mount Wilson, which at one point were dangerously close to the flames, appeared safe, she said.
"They say Mount Wilson is prepped better than it's been in about the last 100 years," 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 for Capt. Tedmund Hall and Specialist Arnaldo Quinones. The fallen firefighters 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.