The slow-moving 5,222-acre brush fire burning in a federal preserve on the southern tip of Riverside County, along the boundary with San Diego County, is 82% contained Monday and has destroyed 23 structures, authorities said.
Full containment was expected by Wednesday, the Cal Fire/Riverside County Fire Department announced.
"Fire crews strengthened control lines and made excellent progress within the fire line. With elevated temperatures and dry weather, unburned vegetation within the perimeter of the fire burned and produced visible smoke. Resources continue to work diligently to establish containment lines," fire officials said in a statement Sunday.
The public was advised to use caution near the perimeter of the fire.
Officials previously confirmed the fire was triggered by a faulty electrical panel on private property.
"Cal Fire peace officers, after an origin and cause investigation, determined the cause of the Nixon Fire was electrical, caused by a privately owned electrical panel," according to an agency statement released Friday.
The fire has damaged three structures and threatened 129 more, prompting an evacuation order for the scattered homes south of Highway 371, north of the county line, west of Terwilliger Road and east of Foolish Pleasure Road.
No injuries were reported.
Bradford Road at Highway 371 remained closed as of Sunday night.
At its peak, an estimated 1,783 structures were threatened. As of late Friday, the fire was no longer threatening any homes or other structures situated within the Beauty Mountain Wilderness, which is maintained by the U.S. Bureau of Land Management.
A temporary evacuation center was established at Hamilton High School, 57430 Mitchell Road in Anza, with staffers available to assist with animals.
People needing after-hours help with animal evacuations should call 951-358-7387.
The blaze erupted about 12:30 p.m. Monday in the area of Richard Nixon Boulevard and Tule Peak Road, according to the Riverside County Fire Department.
There were 990 people battling the blaze as of Saturday night, including county fire crews, Cal Fire-San Diego County crews and BLM firefighters.
