On September 11 , 2001 , two of the four hijacked planes were flown into the Twin Towers of the original World Trade Center , and the towers collapsed . The 7 World Trade Center was not struck by a plane but collapsed because of heavy debris falling from the impacts of planes and the collapse of the North Tower . The other buildings of the World Trade Center complex were damaged beyond repair and soon after demolished . The collapse of the Twin Towers caused extensive damage to surrounding buildings and skyscrapers in Lower Manhattan , and resulted in the deaths of 2,606 people , in addition to those on the planes . Many rescue workers and residents of the area also developed several life-threatening illnesses and some have since died
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United Airlines Flight 93
Lower Manhattan