Swiss authorities say a deadly fire at a ski resort bar in Crans-Montana, Switzerland, quickly developed into a “flashover”, a dangerous phenomenon in which everything in the room ignites at almost the same time.
Béatrice Pilou, attorney general of Valais, said on Friday that the fire was likely caused by a sparkler from a champagne bottle that landed too close to the ceiling and quickly developed into a “flashover fire.”
According to the US-based National Fire Protection Association (NFPA), a flashover occurs when hot gases rise to the ceiling and spread across walls. The heat then increases further until all flammable materials in the room reach their ignition point and ignite.
Officials are also discussing “backdraft” as another potential factor in why the fire spread so quickly. According to the NFPA, a backdraft is an explosion that occurs when oxygen is introduced into a room filled with hot gases.
When temperatures rise to 1,000 degrees Fahrenheit, even firefighters wearing full protective gear are unlikely to survive, NFPA said.
Independent fire consultant Stephen McKenzie told CNN on Friday that when a flashover occurs, it creates ripples of smoke that spread laterally across the ceiling and begin to “preheat” everything in front of it.
As the fire spreads, it begins to require more oxygen, McKenzie said.
If an opening was created to let oxygen in, such as a door opening as people tried to escape, it could have created a “chimney effect” accelerating the upward flow of smoke and flammable gases, he said.
“A layer of hot gas is developing and heat is radiating into my body. People are starting to realize that I have to get out of here,” he said.
McKenzie said the fire would also produce a mixture of flammable gases that would start the fire. “The smoke is actually burning,” he said.
Asked how long it would take for a flashover to occur, McKenzie offered a grim prediction. “A few seconds,” he said. “We’re looking at seconds to minutes.”
Medical staff said Friday that some of the people hospitalized appeared to have injuries consistent with flashover.
“Most of the patients appear to be victims of flashover and have injuries typical of this phenomenon,” a Geneva University Hospital (HUG) spokesperson told CNN, adding that backdraft was also a possibility.
Dr. Robert Laribau, HUG’s head of emergency services, said flashover victims usually suffer severe burns, “primarily affecting exposed body parts such as the face, neck and upper extremities.”
Backdraft injuries, on the other hand, typically include “severe blast trauma, extensive thermal damage, and inhalation of deadly toxic gases,” he said in a statement.
CNN’s Martin Goilandeau, Caitlin Danaher, Mitchell McCluskey and Lauren Chadwick contributed reporting.
