(CNN) -- About 300 firefighters Wednesday battled a wind-driven brush fire that has consumed about 170 square miles of land at the Idaho National Laboratory's desert site, the INL said.
The fire, which has been burning since Tuesday afternoon, was fought on four fronts. Crews were concentrating late Wednesday on an active fire on the northeastern corner of the property, south of Mud Lake.
Officials dispatched 28 fire engines, a helicopter, nine bulldozers, five air tankers and other equipment, the agency said. The only injury Wednesday was a firefighter who suffered a sprained back.
The cause of the Jefferson Fire about 40 miles west of Idaho Falls was unknown Wednesday afternoon.
About 80 percent of the 109,000 acres belongs to the U.S. Department of Energy. Forty percent of the fire on the DOE property was contained and crews were monitoring hot spots, said INL spokeswoman Barbara Morris.
"We are pleased that we have been able to protect our buildings and facilities," said INL Emergency Director Riley Chase. "If the weather conditions hold, we will continue to gain ground on containing the fire today."
INL is an applied engineering national laboratory supporting the U.S. Department of Energy's missions in nuclear and energy research, science and national defense.
"It's an eye-opening fire because it's so large," said Ken Frederick, spokesman for the National Interagency Fire Center in Boise.
Frederick said there are threats to structures in the Idaho National Laboratory and some of the employees have been relocated.
Meanwhile, firefighters on Wednesday were conquering two wildfires that had been burning in southern California since the day before, shutting down roads and prompting some residential evacuations.
Crews expected to fully contain a 68-acre fire in Camarillo, California -- about 50 miles northwest of Los Angeles -- by noon and completely put it out by 6 p.m., according to Bill Nash of the Ventura County Fire Department.
He said the 100 or so firefighters on the scene were concentrating on mop-up work and damage assessment Wednesday
All the evacuations forced by the fire were lifted, he said.
Meanwhile, a 3,000-acre fire at Camp Pendleton -- a U.S. Marine Corps base north of San Diego -- was 80 percent contained Wednesday afternoon, according to a statement from the base public affairs office.
The Camp Pendleton fire, which started Tuesday morning during a training exercise, forced one road closure, but the road was reopened Wednesday.
CNN's Lynn Lamanivong and Nick Valencia contributed to this report.