As the workday was ending on the afternoon of Saturday, March 25, 1911, a fire flared up at approximately 4:40 PM in a scrap bin under one of the cutter's tables at the northeast corner of the eighth floor. The first fire alarm was sent at 4:45 PM by a passerby on Washington Place who saw smoke coming from the eighth floor. Both owners of the factory were in attendance and had invited their children to the factory on that afternoon. The Fire Marshal concluded that the likely cause of the fire was the disposal of an unextinguished match or cigarette butt in the scrap bin, which held two months' worth of accumulated cuttings by the time of the fire. Although smoking was banned in the factory, cutters were known to sneak cigarettes, exhaling the smoke through their lapels to avoid detection. A New York Times article suggested that the fire may have been started by the engines running the sewing machines, while The Insurance Monitor, a leading industry journal, suggested that the epidemic of fires among shirtwaist manufacturers was "fairly saturated with moral hazard.” No one suggested arson
Because the managers had locked the doors to the stairwells and exits – a common practice at the time to prevent pilferage and unauthorized breaks – many of the workers who could not escape the burning building jumped from the eighth, ninth, and tenth floors to the streets below.
A bookkeeper on the eighth floor was able to warn employees on the tenth floor via telephone, but there was no audible alarm and no way to contact staff on the ninth floor. The first warning of the fire on the ninth floor arrived at the same time as the fire itself. Although the floor had a number of exits, including two freight elevators, a fire escape, and stairways down to Greene Street and Washington Place, flames prevented workers from descending the Greene Street stairway, and the door to the Washington Place stairway was locked to prevent theft by the workers; the locked doors allowed managers to check the women's purses. The foreman who held the stairway door key had already escaped by another route. Dozens of employees escaped the fire by going up the Greene Street stairway to the roof. Other survivors