The fire began in Holy Jim Canyon in Corona California where Clark lived, and the report noted that of the five cabins that were burned in the blaze that began earlier in the week, only the suspect's remains standing.
Speaking at a dinner with business leaders on Wednesday, the president expressed his support for the families that have lost loved ones in the California fires, and said his administration was working closely with state and local authorities.
He is facing two felony counts of arson, one to terrorize and a misdemeanor count of resisting arrest.
Rob Gore, a firefighter from the Australian capital of Canberra, said it makes for good relationships that Australians often fight fires in North America and that Canadians and Americans regularly fight fires in his country.
Crews braced for "extreme fire behavior" over the weekend, according to the federal fire information website InciWeb.
It moved up through the rugged Cleveland National Forest and down into Riverside County, where it approached thousands of homes.
The Holy Fire, which started started in the Holy Jim Canyon area, has been burning since Monday, with more than 600 firefighters assigned to fight it.
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But the MDC say the security forces have launched a brutal crackdown on the opposition following the disputed poll. The results of the presidential election were announced on Friday last week by the Zimbabwe Electoral Commission.
"This is a monster", said Todd Spencer of the Orange County Fire Authority Board, "who would go out with low humidity and high wind in the highest heat temperatures this time of the year and intentionally set the forest on fire?"
Hundreds more firefighters joined the effort, bringing the total to 1,200.
Lake Elsinore Mayor Natasha Johnson is one of 21,000 residents who was told to leave and fire chiefs are urging people to follow her lead. "Later, he came back and told me what a jerk I was and everyone was after him".
Forrest Clark, 51, made several outbursts, claiming his life was being threatened. Most are on the front lines, using chain saws and hand tools to reduce tinder-dry brush and trees to stop the flames.
The charges can carry a life sentence.
All schools in the Menifee Unified School District in Riverside County were closed Thursday due to poor air quality caused by the fire, and the campuses will remain shuttered Friday.
For two weeks a tiresome haze and the faint smell of smoke from more than a dozen distant blazes have blanketed many California cities, forcing summer campers to stay inside, obscuring normally bright skylines and leaving cars covered with ash.
More than 2,000 properties are at direct risk of the Holy Fire, which is 70 miles south-east of Los Angeles.
Emergency dispatchers reported the fire was 300 acres as of about 4:50 p.m. and the Pit 1 Powerhouse was being evacuated.