The Mountain fire, which has burned 27,500 acres in the mountains above Palm Springs, was sparked by an electrical equipment failure on private property, Cal Fire reported.
The fire was caused by "some type of electrical equipment" on private property, and was not a utility company electrical failure, said Cal Fire Battalion Chief Julie Hutchinson. No other details were available and the investigation is ongoing, she said.
The fire broke out July 15 near the junction of Highway 243 and Highway 74, according to Cal Fire. The blaze burned east of Mountain Center, through the Apple Canyon and Bonita Vista areas, then along the Desert Divide and southern portion of the San Jacinto Wilderness.
Several mountain communities were forced to evacuate, including Mountain Center, Idyllwild, Fern Valley and Pine Cove. Seven homes and 15 other structures were destroyed.
The fire has burned 27,531 acres but is now 92% contained. Full containment is expected by Friday night, officials said.