As he approached Le Constellation bar to celebrate the ‍New Year in a snowy Swiss ski resort bright with Christmas lights, Dominic Dubois saw flames engulfing the building.

“You could see the orange, ‍the orange, yellow, red,” Dubois said, describing chaotic scenes as bystanders and emergency crews worked together to pull victims clear.

He described how people who had managed to escape the burning building were plunged into the cold outside.

“So one of the priorities was to get everyone warm … ‌the curtains of the restaurant were used,” he said.

Dozens of people were killed and around 100 injured when fire tore through the crowded ⁠bar during a New Year’s Eve party in the Crans-Montana resort, officials said on Thursday.

Nearby, local resident ‌Samuel ​Rapp, ‍21, was dining at a Mexican restaurant when he heard of the blaze, and rushed with his girlfriend to Le Constellation, a bar popular with young locals.

“Police and paramedics … had already set up a protective perimeter,” he said. “There were people screaming, and then people lying on ⁠the ground, probably dead. They had jackets over their faces.”

Fire broke out in the bar at 1.30 am local time. ⁠The cause of the blaze, which was initially ⁠reported as an explosion, was not yet clear but authorities said it appeared to be an accident rather than an attack.

Rapp said he had seen ‍videos showing desperate partygoers trampling each other to escape. “People were shouting, ‘help me, please help us.’”

Le Constellation bar is pictured at the end of the cordoned off street after a fire broke out overnight. Photograph: Harold Cunningham/Getty ImagesLe Constellation bar is pictured at the end of the cordoned off street after a fire broke out overnight. Photograph: Harold Cunningham/Getty Images

The local branch of UBS bank opened up to give refuge to survivors, said Dubois, standing at the police cordon on Thursday in a green knitted hat.

“All the tables were pushed aside and people entered and it was warm in there, there was more light as well, so the triage was down there,” he said.

“Paramedics, police – not the firemen, the firemen were out here. And then it was just ambulances coming ‌back and forth as much as ‌possible.”

Video footage showed lines of ambulances queuing and helicopters landing to take victims of the blast to nearby hospitals and specialist burns units in other Swiss cities.

A waiter in a restaurant near ‌the bar, who declined to be named, said first responders approached staff to ask for tablecloths to cover the bodies to conceal them ⁠from onlookers.

The cause of the fire is not yet known. Photograph: Jean-Christophe Bott/APThe cause of the fire is not yet known. Photograph: Jean-Christophe Bott/AP

In daylight on Thursday, the bar was covered in white sheeting with a tent set up outside and a grey hearse parked in front.

A policeman stood guard, next to two festive reindeer. – Reuters