A fire churning through the Angeles National Forest is only 5 percent contained and could take a week to put out. The fire has burned through 3,600 acres and authorities said the blaze has injured four people.

The cause of the fire is being investigated.

Nearly 500 firefighters, 11 air tankers and 10 helicopters have been battling the blaze which reportedly started at around 2 p.m. on Saturday.

County officials said the forest's bush has not burned for nearly 20 years.

"We have some challenges we face out there," Tony Imbrenda, Inspector of the Los Angeles County Fire Department, told reporters. "We expect that this is going to take several days to get some containment."

Firefighters are battling high temperatures and low humidity with wind gusts of up to 25 mph.

There are no residential areas in the path of the fire, but about 12,000 recreational campers were reportedly evacuated from the area.


View Williams Fire in a larger map