III.

September 11 Attacks

On the morning of September 11 two hijacked Boeing 767 commercial jetliners flew into the towers. The airplanes were almost fully fueled, and the intense heat generated by the burning fuel melted the buildings’ steel supporting beams. The south tower stood for about 1 hour after the crash; the north tower for approximately 1 hour and 45 minutes. They then collapsed, floor upon floor, the added weight of each concrete floor causing floors beneath to collapse. Tenants and visitors left the buildings by stairways, but not everyone was able to escape. Nearly 2,800 people died as a result of the terrorist attack, including hundreds of firefighters and police who had arrived to help. The buildings had been designed to withstand a collision from a jet plane, and they had survived a terrorist bomb attack in 1993. But they could not withstand the heat of the burning fuel. All seven buildings in the complex collapsed during the disaster. See also September 11 Attacks.