Dry brush and wind gusts quickly spread the flames, which officials said were sparked just after 10:30 a.m. in the Cajon Pass near Kenwood Avenue, west of Interstate 15.
The blaze spread over bone-dry hillsides and toward the San Bernardino National Forest, destroying homes, businesses, a historic diner and at least one church. An exact tally of the structure damage was not immediately available.
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Gov. Jerry Brown declared a state of emergency in San Bernardino County due to the fire. The proclamation provides more state resources to firefighting efforts and grants certain benefits to affected residents, such as waiver of fees for destroyed documents and faster unemployment benefits.
"There was a clearing there, and we sat there with flames all around us. We had to keep the windows up because we couldn't breathe. The smoke was so thick, and as soon as the smoke cleared, we could see that everything was gone," Crystal Armstrong, who lost her home in the fire, said.
Fire officials said more than 700 personnel were at the scene and stated more have been requested.
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The fast-moving blaze forced several evacuations, including the entire community of Wrightwood, which has about 4,500 residents.
In all, authorities stated 82,000 people had been evacuated and 34,500 homes were affected by the evacuations.
"Got all the dogs out, and the two kitties," evacuee Royce Bordes said frantically. "There are fires all around it (the home). But the firemen are doing a wonderful job."
Six firefighters became entrapped by the wildfire while defending homes in the Swarthout Canyon area, west of Cajon Pass, according to the San Bernardino County Fire Department.
The firefighters were able to take shelter in a nearby structure, but two firefighters suffered minor injuries. The injured firefighters were taken to the hosptial where they were treated and released.
The fire department said the injured firefighters were heading back to the fire line to defend structures. One fire truck sustained moderate fire damage while the firefighters were entrapped.
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A smoke advisory was issued for portions of San Bernardino County, including parts of the San Bernardino Valley and the San Bernardino Mountains.
The cause of the fire was not known.