The so-called Hathaway Fire was reported shortly before noon Sunday near Hathaway Canyon and Morongo roads, east of the city of Banning. The blaze was burning in steep and rugged terrain in the San Gorgonio Wilderness on Monday.
Firefighters said they expected extreme fire behavior. Nearly 1,000 personnel were battling the fire. Nine air tankers and eight water-dropping helicopters were also assigned to the fire. Three injuries were reported.
According to San Bernardino National Forest officials, no structures were threatened, and no evacuations were in place. The San Gorgonio Wilderness area remained open, except for Vivian Creek Trail.
By Monday night the fire had charred 1,650 acres and was 25 percent contained. The cause of the fire remained under investigation.