The 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 on Thursday.
The disaster has killed two firefighters, destroyed 64 homes and torched 145,000 acres, or about 226 square miles (585 sq km).
"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," U.S. Forest Service Commander Rita 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, reports Reuters.