Several people have been killed and a number of others were injured in a fire which broke out in a crowded bar in the luxury Swiss ski resort town of Crans-Montana on New Year’s Eve.

As revellers rang in the new year, a “fire of undetermined origin” broke out in a bar popular with tourists, police in the Wallis canton in southwestern Switzerland, police said in a statement.

“Several people lost their lives and others were injured,” the statement said, describing the incident as “serious” and said “a major emergency response is under way”.

“A large contingent of police, firefighters, and rescue workers immediately went to the scene to assist the numerous victims,” it said.

“The operation is still ongoing.”

Rescuers and people are seen at the site of an explosion that ripped through a bar in Crans-Montana
The area around the building has been cordoned off by police

Swiss daily Blick cited a doctor at the scene suggesting that the death toll could be in the “dozens”.

Regional daily Le Nouvelliste also said its sources were describing “a heavy toll”, with “around 40 dead and 100 injured”.

Images published by Swiss media showed a building in flames, and people screaming and running in the dark.

Swiss media suggested that the fire may have started when pyrotechnics were used during a concert, but police said the cause was unknown.

Police spokesman Gaetan Lathion earlier there had first been an “explosion of unknown origin”.

He said the explosion took place at around 1.30am local time (3am Irish time) in a bar called Le Constellation.

Police said the areas was “completely closed to the public”, and that “a no-fly zone over Crans-Montana has been imposed.