The massive Sesnon fire was sparked when heavy winds downed an electrical distribution line, causing sparking onto dry brush in a drainage ditch, fire officials said Wednesday.
Los Angeles County Fire Department officials said they had tracked the start of the blaze to a remote unincorporated area west of Limekiln Canyon Road.
Calm winds Wednesday kept that and another fire in the San Fernando Valley from making a run toward the sea; the fires claimed two lives, destroyed 49 structures and burned more than 18,000 acres. "This is our top priority right now to put out these fires, even though we have our financial problems in the state," Gov. Arnold Schwarzenegger said Wednesday in a news conference at the command center in Thousand Oaks. "We are not sparing one single dollar or dime."
The governor has also declared a state of emergency in San Bernardino County. Los Angeles and Ventura counties were given that designation earlier this week.
The cost to date of fighting the Sesnon fire is $2.5 million. It started Monday in Porter Ranch and grew to 13,825 acres. Light winds were allowing firefighters to make headway in containment on the fire's eastern flank.
Of the 20 largest wildfires in California history, power lines were suspected in or blamed for four, accounting for about 21% of the charred acreage, according to statistics from the state Department of Forestry and Fire Protection.
Los Angeles County fire officials said Wednesday that the downed power distribution line believed responsible for the Sesnon blaze was privately owned, but they did not identify the owner.
A government source familiar with local power distribution systems said it was unusual to have private ownership of power lines and poles.
Although Southern California Edison serves the area affected by the fire, spokesman Steve Conroy said Wednesday that the company does not own the power line involved in the fire and that he could not confirm whether Edison provided service to the private line.
"Edison facilities were not involved with this fire," Conroy said. "We don't maintain or service that particular private distribution circuit."
State regulators require utilities to clear brush and meet pole strength standards to help prevent the downing of power lines. Los Angeles County Fire Chief P. Michael Freeman said one aspect of the investigation would examine whether the private owners properly cleared the brush and whether state regulations applied to the private owner.
Also on Wednesday, a small fire broke out on a remote hillside in the Anaheim Hills area, and Orange County authorities used aircraft to fight it.
Fire crews estimate they will have the Sesnon blaze fully contained by Saturday, said Nick Cerciello, a spokesman for the combined agencies fighting the fire. It was 50% contained Wednesday, and no structures were threatened.
Del Walters, chief of the forestry department, said that because the fire had not yet been fully contained, there was still some chance it could spread if winds picked up again.
"The winds are down now, but humidity is very, very low and temperatures are warm, so there is still a danger of it spreading," he said.
Bob Roper, chief of the Ventura County Fire Department, cautioned: "We are not out of fire season. Fire season is year-round now."
The Marek fire, which started in the foothills of the Angeles National Forest, was 92% contained Wednesday, and all evacuations were lifted, said Lisa Lugo, a Forest Service spokeswoman. Full containment of the 4,824-acre blaze was expected today, she said.
In San Diego County, the Juliet fire at Camp Pendleton spread to 3,600 acres and was 60% contained. Close to the Mexican border east of San Diego, the 200-acre Shockey fire broke out early Tuesday near California 94 but was 70% contained by evening. A fire in the Little Mountain area of San Bernardino County was contained at 100 acres.
The Porter Ranch fire burned in an area that has repeatedly been scorched by wildfires driven by Santa Ana winds.