Witnesses blame 'sparklers in champagne bottles' after 40 killed in Swiss Alps blaze

An Australian is among the injured after the international ski and golf venue bar morphed from a scene of revelry into the site of one of Switzerland's worst tragedies.

New Year celebrations turned to tragedy in Switzerland on Thursday, with dozens of people dead and more than 100 others injured in a fire at an Alpine ski resort described by officials as one of the worst tragedies the country has experienced.

Authorities said the blaze broke out in the early hours of New Year's Day at Le Constellation bar in Crans-Montana, one of Switzerland's most exclusive locales.

Authorities did not immediately have an exact count of the deceased.

READ MORE: Three drowning deaths, two people missing in horror 36 hours in NSW

Australia's Department of Foreign Affairs and Trade has confirmed one Australian is among the injured.

"We extend our deepest condolences to those affected by the devastating fire at the 'Le Constellation' bar in the Crans-Montana ski resort in the Swiss Alps," a DFAT spokesperson said in a statement.

"The Department of Foreign Affairs and Trade (DFAT) is providing consular assistance to the family of an Australian that has been injured and is receiving medical care following the fire."

The spokesperson said the department was making enquiries to determine whether any other Australians were impacted.

READ MORE: Aussie cattle farmers dealt blow as China slaps cap on beef imports

What happened?

Le Constellation lies at the heart of the luxury ski resort, just a short walk from the bottom station of the lift that takes skiers up into the mountains.

It has two bars, a dedicated shisha smoking area, and a capacity of 300 people, with terrace space for 40, according to its website.

Photos from inside the venue show a dark, cavernous space with a large, brightly lit bar at its centre.

READ MORE: Former Victorian premiers join call for Bondi terror attack royal commission

It was not immediately clear which part of the bar was affected by the fire.

Valais Cantonal Police Commander Frédéric Gisler said Thursday evening that smoke was first spotted around 1.30am local time (11.30am AEDT) and emergency services were called.

Police were on scene within two minutes of the alarm being raised, and were quickly supported by firefighters and other emergency responders from the region, he told a press conference.

Two witnesses told CNN affiliate BFMTV they thought the devastating incident was caused by sparklers placed in champagne bottles.

"There were waitresses carrying champagne bottles with sparklers on them, and they carried them close to the ceiling, which caused it to catch fire," one eyewitness said.

"One waitress was standing on another waiter's shoulders, and the bottle and the flames were just a few centimetres away from the ceiling," the other reveler added.

"Once the ceiling was on fire, within about 10 seconds the entire nightclub was on fire," the first eyewitness said. "We all ran out screaming and when we turned back, there were flames."

Both witnesses said there were at least 200 people inside the establishment.

Officials on Thursday said the total number of revelers at the New Year's Eve event is currently unknown, but will be part of the ongoing investigation.

When questioned by a journalist at a news conference about the origin of the fire and whether the staircase between the two floors of the bar was "very narrow," Attorney General Béatrice Pilloud said she could not comment on reports that a sparkler was the ignition source and that it was too early to determine what exactly started the fire.

"Concerning the narrowness of the stairs… the investigation will also determine if all the safety standards were complied with or if it wasn't the case," Pilloud also said.

Another eyewitness recalled hearing people shouting as the fire tore through the bar.

"There were people screaming, and then people lying on the ground, probably dead. They had jackets over their faces," local resident Samuel Rapp told Reuters.

He continued: "Then I received videos where people were trying to get out, but they were trampling over each other, so it was hard to get out through the exit. And there were people shouting, saying, 'Help me. Please help us.'"

Axel Clavier, a 16-year-old from Paris who survived the blaze, described "total chaos" inside the bar.

One of his friends died and "two or three" were missing, he told The Associated Press.

He said he hadn't seen the fire start, but did see waitresses arrive with Champagne bottles with sparklers, he said.

Clavier said he felt like he was suffocating and initially hid behind a table, then ran upstairs and tried to use a table to break a Plexiglas window. It fell out of its casing, allowing him to escape.

He lost his jacket, shoes, phone and bank card while fleeing, but "I am still alive and it's just stuff."

"I'm still in shock," he added.

READ MORE: Queen Camilla reveals indecent assault as a teen for first time

Police have released footage from inside the venue, which appeared to show the terrace area of Le Constellation.

Chairs and benches could be seen in disarray, suggesting the panic of partygoers as they attempted to flee the blaze.

Operations are ongoing and the area has been closed off, with a no-fly zone in place over Crans-Montana, police said.

While the investigation is in its early stages, police have ruled out a terror attack, saying the tragedy is being treated as a fire.

Pilloud told the news conference that the investigation will determine the circumstances of the fire and that it will take time.

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

"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.

The injured were so numerous that the intensive care unit and operating theatre at the regional hospital quickly hit full capacity, Reynard said.

Crans-Montana is less than five kilometres (three miles) from Sierre, where 28 people, including many children, were killed when a bus from Belgium crashed inside a Swiss tunnel in 2012.

How many people lost their lives?

Around 40 people were killed and a further 115 injured, many of them severely, police said in Thursday evening's news conference.

Authorities were still working to identify all of the deceased and injured victims, and the victims are likely of several different nationalities.

Families of those involved face an agonising wait after authorities said it could "take several days" to identify all of the victims.

President of the Swiss Confederation Guy Parmelin said the incident represented a "tragic loss that touches the whole country and far beyond," as he offered his condolences to the victims and their families.

New Year's Day was the first day of Parmelin's one-year term as head of state; he postponed a traditional address to the nation out of respect for the victims of the fire.

French President Emmanuel Macron also offered his condolences to the bereaved, saying Switzerland has "the full solidarity of France and our fraternal support."

Resort town sits in the heart of the Alps

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.

With high-altitude ski runs rising around 3000 metres (nearly 9,850 feet) 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.

The resort will host the best men's and women's downhill racers, including Lindsey Vonn, for their final events before the Milan-Cortina Olympics in February.

The town's Crans-sur-Sierre golf club stages the European Masters each August on a picturesque course.

The Swiss blaze on Thursday came 25 years after an inferno in the Dutch fishing town of Volendam on New Year's Eve, which killed 14 people and injured more than 200 as they celebrated in a cafe.

Swiss President Guy Parmelin, speaking on his first day in office, said many emergency staff had been "confronted by scenes of indescribable violence and distress."

"This Thursday must be the time of prayer, unity and dignity," he said.

"Switzerland is a strong country not because it is sheltered from drama, but because it knows how to face them with courage and a spirit of mutual help."

- with reporting from Associated Press and CNN