Credit: via X
The New Year's Eve party was well under way when tragedy struck.
As around 200 revellers were celebrating in the packed basement of Le Constellation bar, a barmaid carrying a champagne bottle topped with a sparkler made her way through the crowd.
The barmaid, carried on the shoulders of a colleague, held the bottle above her head near the basement's ceiling, setting it alight, witnesses said.
Footage taken inside shows theflames rapidly spreading along the roofabove the bar as the music continues playing at around 1:30am local time on New Year's Day. A crowd of party-goers, the vast majority being aged between 15 and 20, rushed to escape via a narrow flight of stairs through a single door.
Credit: via X
Others tried to smash windows to escape as the fire started spreading to the ground floor. But many were left trapped inside after the basement's ceiling collapsed on top of them, witnesses said.
Several dozens of people were killed and 100 seriously injured in the fire. Many of the victims are believed to have been trapped, with reports suggesting there were not enough emergency exits.
Police are investigating whether the bar, which videos show was densely packed, had exceeded the legal limit on the number of customers.
Emma, a French witness, said the fire spread "in seconds".
"Some of the bottles were near the ceiling and it caught fire. The whole ceiling was in flames and the fire spread really fast. It happened in seconds. We all ran outside, screaming and crying," she told French news channel BFMTV.
"I saw a young man writhing in agony on the floor. His body and his hair were badly burned and half of his face had gone. I think he must have died."
Panic-stricken parents rushed to the scene from around the town and beyond to find out whether their children were trapped inside. Video showed young people piling out of the pub screaming as they escaped the flames and black smoke.
Sitting 25 miles north of the Matterhorn mountain and 81 miles south of Zurich, the upmarket resort town of Crans-Montana is popular with British tourists and visitors from elsewhere, there for the skiing and the party atmosphere.
Billed by some as the "best place to celebrate New Year's Eve" in the town, Le Constellation was packed with young people, largely aged between 15 and 20, witnesses said.
"The party was in full swing ... music and champagne flowing freely," according to one witness.
Lighting sparklers in bottles in the cramped confines of the basement had even featured in a promotional video for the venue posted on social media previously.
It showed waitresses wearing crash helmets walking through the club, waving pyrotechnics flaring out of Dom Perignon champagne bottles precariously close to the beamed ceiling.
Credit: YouTube / Constellation Crans Montana
Another witness, called Albane, said she saw the ceiling catch fire after the firework was lit in the bottle.
"It was clearly accidental," the witness added.
One young man watching from across the street said he saw about 20 people scrambling to escape the smoke and flames.
Likening what he witness to a "horror movie", he told The Telegraph: "We are broken. Apparently there were sparklers. They should be banned."
"How did this happen? I heard screaming after. People ran out everywhere and then fire engines came," he added.
Crans-Montana's local authority had banned fireworks and sparklers during the New Year's Eve celebrations over concerns that a lack of rain over the past month had left conditions dangerously dry, increasing the risk of fires catching and spreading quickly.
A local reported hearing loud explosions coming from the vicinity of the Le Constellation.
"I heard a number of massive bangs, which sounded like bombs going off. It was crazy," they said. "I live hundreds of yards from the bar. I heard screaming and screaming and people running."
Adrien, an eyewitness who was outside the club when the fire broke out, described the horror of watching those inside flee for their lives.
"There was a young man with burns on the pavement outside who kept saying: 'It hurts, I'm in pain, please call an ambulance.'" he said.
Helicopters and ambulances rushed to the scene, with emergency services from neighbouring countries deployed to assist the rescue operation.
Credit: TikTok / ladzdrie92i
The intensive care unit and operating theatre at the regional hospital were overwhelmed with victims and those suffering the worst burns were sent to university hospitals across Switzerland.
With the scale of the tragedy quickly becoming apparent, the authorities called on residents to show caution over the coming days to avoid placing further strain on the medical system.
Michela Ris, the deputy mayor of the Swiss town of Ascona, who was in Crans-Montana to celebrate New Year's Eve, described how she was still frantically searching for friends on New Year's morning.
"Some acquaintances told me about young people leaving the bar covered in blood, some without their clothes. It was a real bloodbath," she told Swiss media.
"We have friends who are not responding to messages. Maybe they are just asleep, but we don't know if, after being at our house, they went straight home or if they went for one last drink, perhaps to the very club where the tragedy took place.
"We are very worried and are trying to contact everyone, one by one, to make sure they are okay. We are devastated."
As morning broke, residents and commuters gathered outside, many in tears, devastated at the night's events in their town.
Around 50 family members were waiting for news on their missing loved ones.
Referring to the sparkler that caused the fire, a bus driver told The Telegraph: "They're banned in a lot of clubs and they should never be allowed anywhere near crowded places. This is an absolute tragedy."
As the region declared a period of mourning Mathias Rénard, head of the regional government, told reporters: "This evening should have been a moment of celebration and coming together, but it turned into a nightmare."
Try full access to The Telegraph free today. Unlock their award-winning website and essential news app, plus useful tools and expert guides for your money, health and holidays.
Caroline Kennedy's daughter Tatiana Schlossberg, 35, 
