Investigators are working to identify the victims of a fire that tore through a bar in the Swiss town of Crans-Montana, turning a New Year's celebration into one of the country's worst tragedies.
It is not yet clear what set off the blaze at Le Constellation, killing around 40 people and injuring at least 115 others, many seriously.
Bystanders described scenes of panic and chaos as people tried to break the windows to escape and others, badly injured, poured into the street.
Swiss police warned it could take days or even weeks to identify everyone who died.
Le Constellation had a capacity of 300 people, plus another 40 people on its terrace, according to the Crans-Montana website.
Swiss President Guy Parmelin called the fire "a calamity of unprecedented, terrifying proportions", and announced that flags would be flown at half mast for five days.
He said authorities were "in close contact with the victims' families, whom we are informing in real time, as well as with the various embassies involved".
"Given the international nature of the Crans resort, we can expect foreign nationals to be among the victims," he told reporters.
The canton's chief prosecutor, Beatrice Pilloud, said significant resources have been deployed "to identify the victims and return their bodies to the families as quickly as possible".
Minister for Foreign Affairs Helen McEntee said yesterday that the Irish embassy in Switzerland is monitoring the situation and will provide consular assistance when required.
She said that any Irish citizen in need of consular assistance can contact the embassy on +41(0) 313500380 or +353 (0) 14082000.
The fire broke out around 1.30am (12.30am Irish time) yesterday at Le Constellation, a bar popular with young tourists.
"We thought it was just a small fire - but when we got there, it was war," Mathys, from neighbouring Chermignon-d'en-Bas said.
"That's the only word I can use to describe it: the apocalypse. It was terrible."
"We've tried to reach our friends. We took loads of photos and posted them on Instagram, Facebook, all possible social networks to try to find them," said Eleonore, 17.
"But there's nothing. No response.
"Even the parents don't know," she added.
Authorities have declined to speculate on what caused the fire, saying only that it was not an attack.
Several witness accounts, broadcast by Swiss, French and Italian media, meanwhile pointed to sparklers that were apparently mounted on champagne bottles held aloft by restaurant staff as part of a regular "show" for patrons who made special orders to their tables.
There were "waitresses with champagne bottles and little sparklers. They got too close to the ceiling, and suddenly it all caught fire", one witness told the Italian media outlet Local Team.
Ms Pilloud said the investigation would look into whether the bar met safety standards and had the required number of exits.
Red and white caution tape, flowers and candles adorned the street where the fire occurred, while police shielded the site with white screens.
After the emergency units at the local hospitals filled up, many of the injured were transported across Switzerland and to neighbouring countries.
The European Union said it has been in contact with Swiss authorities about providing medical assistance, while French President Emmanuel Macron said some of the injured were being cared for in French hospitals.
Italian Foreign Minister Antonio Tajani told Italian broadcaster Rete 4 that around 15 Italians had been injured in the fire, and a similar number remained missing.
The French foreign ministry said nine French citizens figured among the injured, and eight others remained unaccounted for.
Multiple sources said that the bar owners are French nationals: a couple originally from Corsica who, according to a relative, are safe, but have been unreachable since the tragedy.
