Nearly 50 people are dead and more than 100 others were seriously injured after a blaze tore through a crowded New Year’s Eve celebration at a bar in a Swiss Alpine resort, with speculation swirling that the fire was caused by birthday candles.

The fire, which engulfed Le Constellation in the ski town of Crans-Montana, was first reported around 1:30 a.m. Thursday, with firefighters reaching the scene within minutes.

“More than a hundred people were in the building, and we are seeing many injured and many dead,” Swiss police spokesperson Gaëtan Lathion told The Associated Press. “We’re just at the beginning of our investigation, but this is an internationally renowned ski resort with lots of tourists.”

Swiss Confederation president, Guy Parmelin, whose first day in office was on Thursday, said a majority of the victims were young Swiss residents as well as tourists from neighboring countries.

“Behind these numbers are faces, names, families, destinies brutally interrupted,” Mr. Parmelin said at a press conference.

The cause of the blaze — initially reported as an explosion — remains under investigation, though authorities said early evidence suggests it was an accident rather than an attack. Two French women who said they were inside the bar told France’s BFM TV that the fire began in the basement after a bottle containing “birthday candles” was held too close to the wooden ceiling.

“The fire spread across the ceiling super quickly,” one of the women, who identified themselves as Emma and Albane, told BFM TV. The pair said they managed to climb a narrow staircase to the ground floor and escape.

Just minutes later, they said, flames had already engulfed the ground floor as well.

According to other witnesses, the fire ignited when a sparkler carried by a waitress during champagne service set fire to ceiling material above the crowded bar.

Those who survived have recounted disturbing scenes from inside the venue, where people were burned and suffocated by smoke. A witness described to Swiss media outlet 20 Minuten how victims sustained catastrophic burns — their faces severely damaged, hair completely gone, and bodies blackened. Many had clothing melted onto their skin.

Photos from the interior reveal what looks like foam-based acoustic insulation attached to the ceiling, along with widespread use of wood throughout the bar area and staircases.

The venue had previously been given a safety score of only 6.5 out of 10 on a public review site — a fact now attracting scrutiny as authorities investigate why the fire spread with such speed.

Swiss authorities declined to speculate on the cause of the fire, saying only that they ruled out an explosion or foul play as the cause.

“At no moment is there a question of any kind of attack,” Valais Canton attorney general, Beatrice Pilloud, said.