Twin Towers collapse after September 11 attack. Illustration showing the South Tower (left), North Tower (right) of the World Trade Center in New York City, USA, collapsing following the September 11 attacks. Two passenger planes were hijacked by terrorists and flown into the North and South Towers. They impacted the North Tower at 08:46 and South Tower at 09:03. The structural damage caused by the impacts and fires that broke out in the buildings caused them to collapse at 09:59 (South Tower) and 10:28 (North Tower). Building 7 collapsed at 17:21 due to damage and fires caused by the collapse of the North Tower. Many people evacuated safely, but 2763 in the buildings and the surrounding area were killed.