The historic Sperry Chalet in Glacier National Park burned to the ground about 6 p.m. Thursday night after the Sprague Fire went on a run.

“A highly skilled group of firefighters were staged at the Sperry Chalet over the last week. Those firefighters had an extensive hose lay, sprinkler, and pump system installed to protect all of the structures associated with the chalet. The high winds experienced this afternoon pushed the fire to the east. The firefighters, supported by three helicopters, made a valiant stand to save the structure but were unsuccessful in saving the main Sperry Chalet,” the Sprague Fire incident command announced at 6:45 p.m.

On Friday morning, fire information officer Diane Sine provided more details. She said no other structures at the complex, which includes a dining hall, a bathroom, and two cabins, had been lost.

She said six firefighters battled the fire on the ground, while four helicopters were in the air with water drops, but how, exactly, the chalet caught on fire, Sine couldn’t say. Firefighters noticed the chalet was on fire after smoke was seen coming out the closed windows.

The chalet was not fully wrapped with protective material and was not treated with a fire suppressant gel commonly used on homes. The chalet did have some wrap on its lower level, but wrapping the upper floors wasn’t possible, she said, because of its height and size.

She said logistically, it is difficult to wrap a building the size of the chalet. Each roll of the fire resistant material weighs about 100 pounds and the crew couldn’t get to the top of the two-story building.

She said using the gel also presents difficulties, as it has to be maintained and hauled to the site.

Sprinklers were in place and firefighters did wet the roof.

The walls of the chalet are stone and mortar, but the roof is wood as is the interior.

Sine said she couldn’t speak to the condition of the building or whether it was completely gutted or not. She said she hadn’t seen photos of it.

The crew of six was to be replaced with a crew of 10 firefighters on the ground today.

The fire has burned to Lincoln Peak, but had not spilled into the Lake Ellen Wilson Valley. It was also burning down toward Lincoln Creek, but was still about 1,000 feet above the creek itself. The fire also burned over the Snyder Lake campground.

The main threat now is the fire is on Mount Brown just below the lookout and could work downslope toward the Going-to-the-Sun Road.

Helicopters would be working that part of the fire today as well as any other areas where they’re needed, she said.

The fire grew to 4,519 acres, more that doubling on Thursday. The Avalanche Lake Trail is now closed, but the Trail of the Cedars remains open. The Avalanche Campground remains open.

The fire had been growling around the chalet for more than a week. On Thursday, it was stoked by high winds.

The chalet was opened in 1914 by the Great Northern Railway and is one of the most historic structures in the Park. Along with Granite Park Chalet, Sperry Chalet was one of the two remaining backcountry chalets in Glacier, both operated by Belton Chalets, Inc.

The chalet was closed earlier this month due to the Sprague Fire.

The loss is one of the most significant in Glacier Park’s history.