The Sheep Fire in the San Gabriel Mountains charred an 8-mile swath in San Bernardino National Forest and destroyed one home. John Miller, a U.S. Forest Service spokesman, said the fire began in a remote area hundreds of feet from the nearest roads, suggesting arson was more likely than an accident, The Riverside (Calif.) Press-Enterprise reported Tuesday.
"When you look at where it started, you ask, what would start a fire here?" Miller said.
Investigators have ruled out lightning and power lines as possible causes.
The fire began Oct. 3, on a day when it was whipped up by Santa Ana winds. The Forest Service has appealed to anyone who saw suspicious activity in the area that day to come forward.