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10:05 a.m.: The WTC South Tower Collapses
Flames engulf the south tower of the New York World Trade Center after terrorist attack. WTC 2 collapsed an hour later.
Photo © Craig Allen/Getty Images
The intense heat of the jet fuel cannot melt metal, but heat and flames from the crash probably weakened the steel truss system and steel columns around the facade. Because the aircraft landed on lower floors, more weight had to be redistributed from the top floors. By 9:45 a.m. Eastern Time, a witness reported that the floors in the south tower were buckling. Videos confirmed the observations.
The South tower collapsed at 10:05 a.m. Eastern Time. In ten seconds the entire Tower 2 fell upon itself.
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