The Bogart Fire, which officials believe was human-caused, increased in size overnight after breaking out in the Beaumont area Tuesday.
The fire had burned about 1,470 acres and was 60 percent contained as of Wednesday evening, according to the Riverside County Fire Department.
On Tuesday, investigators determined the fire was human-caused after finding footprints and other evidence near Bogart Park, where the fire began about 12:30 p.m.
Officials asked for anyone with information about “juvenile activity” near the north end of Winesap Avenue by the park’s entrance gate to call the Arson Hotline at 800-633-2836.
The blaze burned one out building Tuesday afternoon and forced several communities to evacuate, however, all residents were allowed back into their homes by Tuesday evening.
Two firefighters suffered non-life threatening injuries battling the wildfire, but no civilian injuries have been reported.
More than 400 firefighters were working to contain the wildfire, according to the Fire Department.
KTLA's Cindy Von Quednow contributed to this story.