1,300 acres of California woodland went up in smoke on Sunday after a wildfire blazed out of control in a Los Angeles suburb.
More than a thousand residents of the Pacific Palisades have been forced to evacuate.
Video obtained by Reuters showed helicopters trying to douse the fire with buckets of water, as smoke billowed from the hills.
Local media reported authorities saying that some of the affected areas had old growth that hadn't burned in over 50 years.
Arson investigators and police looked into the cause of the blaze that began Friday, and is now being dubbed the 'Palisades Fire'.
One official with the Los Angeles Fire Department said one of two suspects detained has since been released, while the other is still being questioned.
Mandatory evacuations were also ordered for an area near Topanga Canyon, while other residents are on standby to leave.
There are no reported deaths or casualties so far.