Fire crews lost ground on the Elmo 2 Fire as it made a run toward hundreds of structures in the Lake Mary Ronan area on Wednesday evening.

The human-caused fire west of Flathead Lake grew by about 2,200 acres and was estimated at 20,616 acres Thursday morning. It was 6% contained, with new growth on the northern perimeter.

Eight structures, including four homes, have been destroyed in the fire that is bearing down on Camp Tuffit Road and Lake Mary Ronan. As many as 250 structures are threatened in the area, according to the Northern Rockies Coordination Center.

Crews were expected to focus efforts Thursday on Camp Tuffit Road, and they hoped to hold the fire as it approaches the southeast shore of Lake Mary Ronan.

Air resources were to be used as conditions allow. Three helicopters, six scoopers and two single-engine air tankers were assigned to the blaze.

Total personnel battling the Elmo 2 Fire increased to 439 on Thursday. It is the largest fire in the state, with resources costing about $5 million since the fire began July 29.

Officials closed Lake Mary Ronan Road to all traffic Thursday to allow fire personnel to safely conduct operations.

An evacuation order remains in place for all residents north and south of Lake Mary Ronan Road, and all residents who live along Lake Mary Ronan.

Pre-evacuation warnings are still in effect for residences east and south of U.S. 93 between intersections with Montana 28 and Lake Mary Ronan Road.

Dangerous fire conditions prompted officials to pull firefighters off the north flank Wednesday afternoon as winds caused upslope runs and torching.

More critical fire weather is likely Thursday between noon and 9 p.m., the National Weather Service warned, with sustained winds up to 25 mph fanning the fire from the west. Gusts around 40 mph are possible.

In response to the worsening fire conditions the CSKT Division of Fire enacted Stage 1 fire restrictions for the Flathead Reservation on Wednesday. This prohibits campfires except within a developed site, and limits off-road vehicle travel and smoking.