About an hour before midnight, the club was engulfed in flames because of a spark set off by pyrotechnics. Some witnesses said there was an explosion, but this was disputed and later dismissed by other sources. The club’s ceiling was supported by pillars, which were coated with a flammable soundproofing foam. Soon after the pyrotechnics began, the foam on one of the pillars was ignited. The fire spread rapidly to the ceiling, eventually causing it to collapse. Media reported that club-goers initially thought the flames were part of the show and did not immediately react. When the ceiling caught fire, the approximately 200 to 400 people in the club panicked and rushed to the only working exit door at the venue, creating a stampede. The two-part door was only half opened, thus too narrow, so people climbed on top of each other in order to get out. Many of the casualties suffered from leg injuries after being trampled.A witness said terrified concert-goers had to break down the other half of the door to escape, but many people had already suffered burns, or were in respiratory distress. People also smashed windows in order to escape.