Swiss investigators on Friday began an urgent effort to identify victims of a devastating fire that swept through a crowded bar in the Alpine resort town of Crans-Montana, turning New Year’s celebrations into one of Switzerland’s worst peacetime tragedies.

The blaze tore through Le Constellation bar in the early hours of New Year’s Day, killing about 40 people and injuring at least 115 others, many of them critically. Authorities said it could take days or even weeks to formally identify all the victims, prolonging the anguish of families searching for loved ones.

Eyewitnesses described scenes of panic as revellers attempted to smash windows to escape while others, badly burned, staggered into the street crying for help. Police said the exact number of people inside the venue at the time of the fire remains unclear, and it is not yet known how many are still missing.

The bar, popular with young tourists, had a listed capacity of about 300 people, with space for an additional 40 on its terrace. The fire reportedly broke out around 1:30 a.m. local time.

Swiss President Guy Parmelin described the incident as “a calamity of unprecedented and terrifying proportions” and announced that flags would be flown at half-mast nationwide for five days in honour of the victims.

“Behind these figures are faces, names, families and lives brutally cut short or forever changed,” Parmelin said.

Given the international nature of the Crans-Montana resort, authorities said foreign nationals are expected to be among the dead and injured. France, Italy and the European Union confirmed they were working with Swiss officials to support victims, with several injured persons transferred to hospitals in neighbouring countries.

Investigators have declined to speculate on the cause of the fire but ruled out an attack. Witnesses told local and international media that sparklers attached to champagne bottles—often used during celebratory table service—may have ignited the blaze after coming into contact with the ceiling. Prosecutors said safety compliance, including fire exits and crowd control, would form a key part of the investigation.

The street outside the bar was cordoned off with red-and-white tape as flowers and candles were laid in tribute, while police shielded the scene from public view.