What images and videos tell us why Swiss bar fire spread so quickly

Investigators are racing to find out how and why a deadly fire at a bar in a Swiss ski resort on New Year’s Eve spread so quickly.

authorities said at a news conference on Friday Champagne bottle with sparklers attached The fire in the basement of Le Constellation bar in Crans-Montana appears to have been caused by “being too close to the ceiling”.

But why the fire became so violent, killing at least 40 people and injuring 119 others, many seriously, is now a focus for officials, as is the pub’s safety record.

BBC verify has been examining video taken by survivors and bystanders and speaking to fire safety experts for clues as to what went wrong.

Two striking images widely circulated online showed people holding champagne bottles and lit fireworks above their heads, surrounded by a crowd.

One image showed people holding five such bottles aloft as flames began to gather on the ceiling.

The second image is a close-up angle showing a person wearing a crash helmet, holding a bottle containing a lit firework, and sitting on the shoulders of another person wearing a Guy Fawkes mask.

The sparks from this bottle seem to be closer to the ceiling.

BBC verify established that the images were taken just after midnight on January 1 and confirmed that no earlier versions existed, matching them to public photos of Le Constellation – using details including the bar design and unique piping.

And there is no evidence that the images were processed with artificial intelligence (AI).

In other video we verified from the night of the fire, some people in the bar can be seen filming the flames while loud club music plays in the background. In one video, some people are seen shouting as they start sprinting toward the exit stairwell.

On Friday, Valais canton Attorney General Béatrice Pilloud said everything led investigators to believe the fire was caused by fireworks attached to champagne bottles that were “too close to the ceiling.”

Another focus was the foam-like padding in the bar ceiling and whether it met safety standards.

Two fire safety experts told BBC Verify that materials visible in photos and videos of Le Constellation appeared to show “egg carton foam”, a sound-absorbing material made from polyurethane (PU).

In the photo of the bottle being held up, part of the flames could be seen on the ceiling, which was covered with foam-like coverings.

PU foam is often treated with a flame retardant treatment before being installed as silencers in factories and entertainment venues.

But without treatment, it can be highly flammable.

Dr Peter Wilkinson of Loughborough University said: “Once ignited, polyurethane acoustic foam exhibits rapid flame spread over its high surface area profile and produces dense, toxic smoke, significantly accelerating fire spread and reducing available escape time.”

Professor Edwin Galea of ​​the University of Greenwich said that the flame retardant treatment effect of PU foam will weaken over time.

Swiss authorities said they could not confirm what type of foam filling was used in the bar and whether it met safety standards.

at a press conference on fridayofficials spoke of a “flash fire” that occurred at the bar.

Professor Calais explained that this happens when hot gases rise to the ceiling, reach a critical temperature and then ignite the room almost instantly.

Michael Klippel, a fire safety expert at ETH Zurich, said “the chances of surviving a flashover are very slim.”

The agency responsible for overseeing fire safety inspections in Crans-Montana is the Valais Office Cantonal du Feu (OCF). Inspections are conducted by local officials.

Swiss authorities told a news conference that buildings the size of the Constellation Hotel should be inspected annually.

BBC verify has contacted the OCF to request access to previous inspection files.

Authorities said they would also focus on exit routes from the bar, which is divided into two levels – the ground floor and basement. The fire is believed to have started in the basement, where the two photos mentioned above were taken.

Video taken at the time of the fire shows people trying to put out the flames and then trying to climb the narrow stairs out of the basement.

Professor Calais said stair exits could be deadly bottlenecks, with people tripping or being trampled.

He said people who panic in an unfamiliar space are more likely to exit the same way they came in, even if there are other fire exits.

Officials also confirmed that the building had multiple exits, but added that they “cannot currently determine” whether the emergency exits were open or closed at the time.

Stéphane Ganzer, a member of the Valais cantonal assembly, said: “There is more than just one door, although at the time of the fire it seemed that most people left through the front door. But the building is a public place and is obviously equipped with emergency exits.”

Pillou told reporters that the bar’s two French managers were interviewed, as well as people who escaped the fire.

One of the bar’s owners reportedly told local media that the bar had been inspected three times in the past decade and everything was done in compliance with regulations.

Investigators said they also analyzed other videos from the location.

We found a video showing fireworks attached to bottles being used in a bar back in 2024.

In the video, women wearing distinctive crash helmets hand bottles and sparklers to customers before removing them and pouring drinks.

The video was uploaded to YouTube in May 2024 by the account @ConstellationCransMontana, but we are unable to determine when it was filmed.