Los Angeles ( CNN ) -- It 's already torched more than 35 square miles -- and the massive mountain fire in southern California is nowhere near under control . The blaze , near Idyllwild and Fern Valley , prompted an evacuation order for about 6,000 residents , fire officials said . More than 4,000 homes south of Palm Springs are threatened by the fire . Fewer than 5 % of residents refused evacuation orders , officials said . U.S. Forest Service spokeswoman Jeanne Pincha-Tulley said the blaze was `` human-caused '' and is under investigation . As of Thursday evening , the inferno was about 15 % contained . It has burned 22,800 acres -- up from the nearly 20,000 acres reported Wednesday night , officials said . About 3,000 fire personnel were at the scene , U.S. Forest Service spokeswoman Melody Lardner said . Three firefighters suffered minor injuries Wednesday . At least eight structures have been damaged or destroyed in the blaze . CNN '' s Amanda Watts and Miguel Marquez contributed to this report .
NEW : Blaze is `` human-caused , '' officials say . The fire is threatening more than 4,000 homes . About 6,000 residents in the Idyllwild area are under an evacuation order . The blaze is 15 % contained , a forest service officials say .