IDYLLWILD, Calif. -

The containment of the Mountain Fire was to have been completed today, but full containment will not occur until Friday, the U.S Forest Service announced.

The blaze was 91 percent contained this morning, having scorched 27,531 acres of the San Bernardino National Forest since breaking out near Idyllwild nine days ago. A U.S. Forest Service statement said the cost of fighting the fire had risen to $24.3 million.

The fire's acreage has changed little since Sunday, thanks to rain from thunderstorms over the past few days. The area is expected to dry out today and Thursday.

``As the burn area dries out and warms up, smoke may become visible from the interior of the fire,'' according to a Forest Service statement.

The number of fire personnel assigned to the blaze continues to be reduced, with 767 remaining as of this morning. There are nine engines, 17 hand crews and three bulldozers still assigned to the fire. Six helicopters remain available if needed, officials said.

The blaze has claimed 23 structures, including seven homes, but no major injuries have been reported.

The fire is believed to have started around 1:45 p.m. on July 15 near the junction of Highways 243 and 74. The 23 structures swallowed by the blaze were all destroyed on the first day of the fire.

The cause remains under investigation. Jeanne Pincha-Tully, a U.S. Forest Service fire chief, said last week that the fire was determined to be ``human-caused.''

Evacuations that affected as many as 6,000 people were lifted on Sunday, although the Riverside County Fire Department on Monday issued an evacuation warning for residents to voluntarily leave the area of Apple Canyon Road north of Bonita Vista Road because of possible flash flooding and debris flows in the fire-denuded area.

The Palm Springs Aerial Tramway, which closed Thursday due to fire-generated smoke, reopened Tuesday. The nearby Mount San Jacinto State Park and Wilderness Area, several campgrounds, Humber Park and Pacific Crest Trail and its connecting trails remain closed.