IDYLLWILD, Calif. -

Fire officials today pushed back the estimated full containment date for the Mountain Fire to Tuesday, saying ``extreme terrain'' is making fire line construction difficult.

The fire has scorched 27,531 acres in the San Bernardino National Forest since it broke out south of Idyllwild 11 days ago, when electrical equipment failed on private property near Mountain Center.

As of today, containment was at 92 percent, although full containment had been previously expected today. A statement from the U.S. Forest Service said crews ``are continuing to improve fire line and extinguishing hot areas close to the fire's edge'' and people may see smoke toward the north end of the blaze.

The area is also under a flash flood watch today, with a chance of thunderstorms.

The cost of fighting the fire, which burned in steep areas covered by chaparral and timber, was $25.2 million. But the number of fire personnel assigned to the blaze continued to be pared back, with 146 remaining.

The fire had been under the unified command of the Forest Service and Cal Fire, but on Thursday management was turned over to a San Bernardino National Forest local team.

The fire is believed to have started near the junction of Highways 243 and 74 around 1:45 p.m. on July 15. That day, the blaze claimed 23 structures, including seven homes, but no major injuries were reported, either then or since.

The California Department of Forestry and Fire Protection disclosed Thursday that the blaze was sparked by electrical equipment failure ``on the customer side of the meter.'' It said no more information would be released because an investigation was continuing.

Evacuations that affected as many as 6,000 people were lifted on Sunday, and the Palm Springs Aerial Tramway, which closed July 18 due to fire-generated smoke, reopened Tuesday.

But the nearby San Jacinto Wilderness Area and Mount San Jacinto State Wilderness and all Forest Service Campground and day-use areas along Highway 243 remained closed. Also closed were the Devils Slide, South Ridge, Deer Springs, Marion Mountain, 7 Pines, Black Mountain and Fuller Ridge trails, as well as the Pacific Crest Trail from Highway 74 to Strawberry Junction and connecting trails.

All hiking and mountain biking trails out of the Hurkey Creek County Campground and May Valley areas were also closed, although the Hurkey Creek Campground remained open for camping. Idyllwild and Stone Creek state parks were open, as are the Lake Hemet Campground.

There were no closures on highways 243 or 74.