At least 40 people were killed and nearly 100 others injured after a powerful explosion followed by a fire ripped through an upscale ski resort in Switzerland’s Crans-Montana region late Wednesday night, international media reported.

The incident occurred during a New Year’s Eve celebration at around 1:30am local time at a venue named “Constellation,” where a party was underway. According to preliminary information from Swiss police, the casualties were confirmed by Italy’s foreign ministry.

Authorities said the explosion triggered a rapid spread of fire inside the establishment, causing severe burn injuries. Due to the extent of the burns, many victims could not be immediately identified.

Police have so far found no evidence suggesting the fire was deliberately set. However, local media reported that fireworks used during a concert at the venue may have sparked the blaze.

Valais Cantonal Police chief Frédéric Gissler told a press briefing, “This incident has left us all deeply shaken.”

Following the explosion, the entire area was sealed off and a temporary no-fly zone was imposed over the resort. Rescue and medical operations involved 10 helicopters and 40 ambulances, authorities said.

A police helpline has been opened to assist families searching for missing relatives.

Crans-Montana, located in Switzerland’s Valais region, is one of the country’s most prestigious ski destinations, boasting approximately 87 miles of ski trails. The resort is scheduled to host the FIS World Cup speed skiing events later this month.