The U.S. Forest Service says that the 147,000-acre wildfire in California that has killed two firefighters was started by arson, the Los Angeles Times reports. Officials are searching for whoever started the fire that has destroyed more than five dozen homes. Firefighters made progress in fighting the largest fire in Los Angeles County history Wednesday night, but aggressive arms of the fire are still pushing to mountains above Pasadena, Sierra Madre and Monrovia. Even with the so-called Station fire is now 38 percent contained, crews are still battling to protect well-known campgrounds, trails, recreation areas, and the Stony Ridge Observatory in North L.A. They are also fighting the western leg of the fire, which has pushed toward Pacoima Canyon, prompting the evacuation of 11 homes. Wednesday night a firefighter on the front lines suffered a fractured femur. Meanwhile, one official said the blaze was human-caused, but officials aren't sure if it was arson or an accident.