Around 40 people have been killed and 100 injured after an explosion tore through a crowded bar during a New Year’s Eve party in the upscale ski resort of Crans-Montana in southwestern Switzerland, Swiss police said on Thursday.

The fire broke out at 1.30 am in a bar called “Le Constellation” in Crans-Montana, where police, the fire brigade and rescue services were deployed to help victims.

The area has been completely closed off, and a no-fly zone has been imposed over Crans-Montana, police said in a statement, adding that the cause of the blast remained unclear.

A spokesperson for the southwestern Switzerland police, Gaëtan Lathion, said that an investigation into the explosion is underway.

“Several people are injured, and several have lost their lives,” he said.

According to officials, the explosion occurred at approximately 1.30 am local time, as people were celebrating the New Year.

Crans-Montana is a luxury ski resort town located in the heart of the Swiss Alps, roughly two hours from the Swiss capital, Bern.

Foreign media reports indicate that the blast was so powerful that nearby building windows shattered, spreading panic across the area.

The BBC also confirmed that multiple people had been killed and injured in the explosion.

A helpline has been set up by the authorities for families of those affected.

Unverified footage circulating on social media showed a fire burning at a bar where New Year’s Eve celebrations had been taking place.