Near the south exit close to the main bar, opposite end of the building from the Cabaret Room, a wedding reception drew to a close around 8:30 p.m. in the Zebra Room, near the building's main entrance; some of its guests had complained of the room being excessively warm with loud explosions from beneath the floor, and the group left the building before the end of their allotted time. The room remained vacant from their departure until a minute before 9:00 p.m., when an employee smelled smoke and opened the Zebra Room's door to confirm the presence of smoke. She asked another employee to call the Fire Department while she and others grabbed fire extinguishers and began trying to fight the flames. Though the employees were not aware of it, their opening of the Zebra Room's door allowed enough oxygen into the room to cause what had been a smoldering fire in the room's drop ceiling to flashover and begin to spread rapidly. It quickly became clear that fire extinguishers were useless against the fast-growing blaze. The Fire Department was alerted to the fire at 9:01 p.m. and arrived by 9:05; as they approached, firefighters on the first emergency vehicles could already see smoke coming from the building.