Swiss emergency services responded to an explosion and fire that killed 40 people and injured about 100 during New Year's celebrations at a bar and lounge called Le Constellation, located in the ski resort town of Crans-Montana in southwestern Switzerland.

Local officials said the cause of the blast at Le Constellation remains unclear and noted that it has not been designated as a terrorist attack.

"At the moment, we are considering this a fire, and we are not considering the possibility of an attack," prosecutor Beatrice Pilloud told reporters, adding that a full investigation has commenced.

Latest details from the Swiss news conference:

• Around 40 people are presumed dead, with at least 100 injured

• Victims include multiple nationalities

• Most of the injured sustained severe burns and significant injuries

• Swiss emergency services deployed 10 helicopters, 40 ambulances, and 150 responders to the scene

• Authorities did not disclose a cause for the fire, but the prosecutor ruled out a terrorist attack

• The Valais hospital intensive care unit is at capacity, with patients being transferred elsewhere for specialized burn treatment

"What was meant to be a moment of joy turned, on the first day of the year in Crans-Montana, into mourning that touches the entire country and far beyond," Swiss Federal President Guy Parmelin wrote on X.