A huge wildfire burning in the mountains above Los Angeles, now the largest ever in the county, was started by arson and will be investigated as a homicide, authorities said.
The so-called Station Fire has killed two firefighters, destroyed 64 homes and torched an area the size of Chicago in the nine days it has roared across the rugged San Gabriel Mountains overlooking Los Angeles.
"After a forensic examination at the point of origin, arson investigators have concluded that the Station Fire was the result of an act of arson," US Forest Service Commander Rita Wears said.
The deaths of Los Angeles County Fire Capt. Ted Hall and firefighter Arnaldo Quinones, who were killed when their vehicle plunged 244m from a road, made the case a homicide, Ms Wears said.
Authorities did not offer details about how the fire was started but an area near the city of La Canada-Flintridge, north of Los Angeles, has been cordoned off with yellow crime scene tape since Wednesday.
It was not clear if any suspects had been identified.
As of yesterday evening, the Station Fire had blackened 145,000 acres, or about 585 sq km, making it the largest wildfire recorded in Los Angeles county. It could ultimately become one of the top 10 in state history, in terms of size.
Authorities estimated containment of the massive conflagration at 38 per cent, up from 28 per cent a day earlier, according to fire commander Mike Dietrich, who said his force of more than 4,700 firefighters was making "great progress."
By Wednesday night, the all-clear had been given for the last of 6,400 evacuated households to return home.
The Station Fire has cost $21 million so far to fight, making it the most expensive of several California wildfires in recent weeks that already have depleted the cash-strapped state's emergency firefighting budget by more than half.
Governor Arnold Schwarzenegger has insisted the state has plenty of resources at its disposal for such emergencies.
Reuters