Investigators are racing to determine what triggered the deadly New Year’s fire inside Le Constellation, a crowded bar in Switzerland’s luxury ski resort of Crans-Montana. Authorities say the blaze erupted shortly after midnight and rapidly intensified into a flashover — a phenomenon in which extreme heat causes all combustible material in a room to ignite almost simultaneously. Prosecutors have ruled out terrorism and confirmed that no explosive device was involved, saying the explosion was a consequence of the fire, not its cause. But two French nationals who said they were inside the bar told French media they saw a waitress place a candle or sparkler on top of a champagne bottle during the celebration. According to their account, one of the flames was held too close to the ceiling, which they said ignited within seconds. They described the ceiling catching fire almost instantly, with flames spreading rapidly across wooden surfaces, making evacuation extremely difficult due to narrow stairways and escape routes. Officials stress that these accounts have not yet been confirmed by investigators, and caution that determining the exact cause will take time. Fire safety standards, ceiling materials, crowd density, and emergency exits are all expected to be examined as forensic teams work to reconstruct how a moment of celebration turned into a catastrophe that killed around 40 people, injured more than 115, and overwhelmed Switzerland’s medical system — forcing cross-border transfers of burn victims across Europe.