Crans-Montana, Switzerland — A fire at a bar in the Swiss Alps left many people dead and injured during New Year's celebrations, police said early Thursday.

"Several tens of people" were presumed dead and about 100 more injured, most of them seriously, after the blaze tore through a bar during a New Year's celebration in the Alpine ski resort municipality of Crans-Montana, Switzerland, police said.

Specific casualty figures were not immediately available after the blaze at the bar called Le Constellation.

Beatrice Pilloud, Valais Canton attorney general, said it was too early to determine the cause of the fire. Experts have not yet been able to go inside the wreckage.

"At no moment is there a question of any kind of attack," Pilloud said.

Helicopters and ambulances rushed to the scene to assist victims, including some from different countries, officials said.

"We are devastated," Frédéric Gisler, commander of the Valais Cantonal police, said during a news conference.

The injured were so numerous that the intensive care unit and operating theater at the regional hospital quickly hit full capacity, according to regional councilor Mathias Rénard.

In a region busy with tourists skiing on the slopes, the authorities have called on the local population to show caution in the coming days to avoid any accidents that could require medical resources that are already overwhelmed.

"The fire started around 1:30 a.m. this morning in a bar called 'Le Constellation,'" police spokesperson Gaëtan Lathion said earlier. "More than a hundred people were in the building, and we are seeing many injured and many dead."

Investigators were working to determine the cause of the fire, police said.

"We're just at the beginning of our investigation, but this is an internationally renowned ski resort with lots of tourists," Lathion said.

Two women told French broadcaster BFMTV that they were inside when they saw a barman carrying a barmaid on his shoulders. The barmaid was holding a lit candle in a bottle that set fire to the wooden ceiling. The flames quickly spread and collapsed the ceiling, they told the broadcaster.

One of the women described a crowd surge as people frantically tried to escape from a basement nightclub up a narrow flight of stairs and through a narrow door.

Another witness speaking to BFMTV described people smashing windows to escape the blaze, some gravely injured, and panicked parents rushing to the scene in cars to see whether their children were trapped inside. The young man said he saw about 20 people scrambling to get out of the smoke and flames and likened what he saw to a horror movie as he watched from across the street.

Officials called the blaze an "embrasement généralisé," a firefighting term describing how a blaze can trigger the release of combustible gases that can then ignite violently and cause what English-speaking firefighters would call a flashover or a backdraft.

"This evening should have been a moment of celebration and coming together, but it turned into a nightmare," said Rénard, the regional government leader.

"What was a moment of joy turned into a tragedy in Crans-Montana last night, felt across the country and beyond," Swiss President Guy Parmelin said in a social media post. "The Federal Council has taken note of this with deep dismay. Its thoughts are with the victims, the injured and their families and it extends its deepest condolences."

The Crans-Montana community is in the heart of the Swiss Alps, just 25 miles north of the Matterhorn.

With high-altitude ski runs at around 1.86 miles in the heart of the Swiss Alps, Crans-Montana is one of the winter sports centers of Switzerland's ski-crazy Valais region, also home to Zermatt, Verbier and other resorts nestled in the snowy peaks and pine forests drawing winter sports enthusiasts from across the planet. The resort is one of the top race venues on the World Cup circuit in Alpine skiing and will host the next world championships over two weeks in February 2027.

In four weeks' time, the resort will host the best men's and women's downhill racers for their last events before going to the Milan Cortina Olympics, which open on Feb. 6.

Crans-Montana also is a premium venue in international golf. The Crans-sur-Sierre club stages the European Masters each August on a picturesque course with stunning mountains views. Le Constellation bar is about 273 yards down the street from the golf club.