Multiple people dead after explosion at Swiss Alps resort bar during New Year's celebrations

'Several' people are reported to have died and others have been left injured following an explosion at a bar in the ski resort town of Crans-Montana, Switzerland.

According to Swiss police, more than 100 people are believed to have gathered at the bar, called Le Constellation, which is located in the luxury ski resort town approximately two hours from the Swiss capital of Bern.

The patrons had just recently rung in the new year and were continuing their celebrations when the explosion occurred at around 1:30 a.m. local time.

Gaetan Lathion, a police spokesperson in Wallis canton, in southwestern Switzerland, told AFP: "More than a hundred people were in the building, and we are seeing many injured and many dead."

Unverified footage circulating on social media claims to have been filmed from the road outside the bar, and appears to show a fire burning inside.

Elsewhere, images apparently from the scene show ambulances and at least one fire engine.

Police have secured the scene of the explosion (MAXIME SCHMID / AFP via Getty Images)

Lathion confirmed that an explosion had taken place in the bar, but said it was of 'unknown origin' so far.

In the wake of the incident, authorities have closed off the area around Le Constellation and imposed a no-fly zone over Crans-Montana.

When asked by BBC News how many people had lost their lives in the incident, a spokesperson for the police said: "We can’t say yet. Several."

Lathion has confirmed that a reception centre and a helpline have been set up for families who may have been impacted by the blast.

He added: “We’re just at the beginning of our investigation, but this is an internationally renowned ski resort with lots of tourists."

According to BBC reporter Silvia Costeloe, who is on the scene, police set up a cordon around the area and began erecting white screens to carry out forensic work.

At least 100 people were in the bar when the blast rang out (MAXIME SCHMID / AFP via Getty Images)

"I spoke to some people who heard the explosion, who then heard hours of ambulances afterwards," Costeloe reported.

"The bar where the fire happened is a real institution here. It's been around for at least 40 years."

Costeloe described the Constellation as a 'really big bar', with TV screens upstairs where customers can gather to watch soccer matches.

"Downstairs it just had a big bar where I suppose yesterday people would have been dancing and drinking," she said. "You go there for beers - it's a kind of young bar.

"It would've been a mixture of young people, Swiss people, people coming up from the valleys to celebrate here in Crans-Montana."

Police have said a news conference on the incident is set to take place early on New Year's Day.