It has been a devastating start to the year in Switzerland, where authorities say around 40 people are dead after a fire ripped through a bar at a Swiss ski resort.

Swiss President Guy Parmelin has described it as "one of the worst tragedies" the country has ever seen, overshadowing what was supposed to be a joyful start to 2026.

Here is what we know about the incident, as authorities investigate the cause of the blaze.

Where and when did this happen?

The fire broke out at the Le Constellation bar, a popular venue at the the Crans-Montana resort.

Located in south-western Switzerland, Crans-Montana is best known as an international ski and golf venue.

With high-altitude ski runs rising around 3,000 meters in the heart of the Valais region's snowy peaks and pine forests, Crans-Montana is one of the top venues on the World Cup circuit.

Authorities were first alerted to the unfolding disaster at 2am local time, only hours after revellers officially welcomed in 2026.

What are authorities saying?

The blaze has the potential to become one of Switzerland's biggest disasters.

Valais Canton police commander Frédéric Gisler told a press conference around 40 people were killed at the bar.

At least 115 others were injured, many critically, as fire tore through the venue.

Many of those at the venue at the time of the blaze were aged between 15 and 20 years old.

Work is underway to identify the victims and inform their families, but "that will take time and for the time being, it is premature to give you a more precise figure," Commander Gisler said, adding that the community is "devastated."

The disaster has marred what was supposed to be a celebratory evening at Le Constellation bar. (Reuters/Valais Canton Police)

What caused the blaze?

Authorities are yet to provide an official explanation for what caused the fire.

Meanwhile, eyewitnesses inside the bar have provided accounts about how the blaze spread through the venue.

Two women told French broadcaster BFMTV that they were inside when they saw a barman carrying a barmaid on his shoulders. 

Swiss authorities are urging locals to be extra careful and avoid injuries to prevent adding extra pressure to overwhelmed hospitals. (Reuters: Pierre Albouy)

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.

Officials say the blaze likely triggered the release of combustible gases that ignited violently and caused what English-speaking firefighters call a flashover or backdraft.

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.

What else have eyewitnesses said?

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.

"This evening should have been a moment of celebration and coming together, but it turned into a nightmare," said Mathias Reynard, head of the regional government of the Valais Canton.

ABC/AP