The twin towers of the World Trade Center collapsed on September 11, 2001, as a result of the September 11 attacks , [ 1 ] in which terrorists affiliated with al-Qaeda hijacked four commercial passenger jet airliners , crashing two of them into the World Trade Center, one into the North Tower (1 World Trade Center) and the other into the South Tower (2 World Trade Center). [ 2 ] The collapse of the twin towers destroyed the rest of the complex, and debris from the collapsing towers severely damaged or destroyed more than a dozen other adjacent and nearby structures. The South Tower collapsed at 9:59 am, less than an hour after being hit by the hijacked airliner, and at 10:28 am the North Tower collapsed. Later that day, 7 World Trade Center collapsed at 5:21 pm from fires that had started when the North Tower collapsed. [ 3 ] As a result of the attacks to the towers, 2,752 people died, including all 157 passengers (including the hijackers) and crew aboard the two airplanes. [ 4 ] Immediately following the attacks, a building performance study (BPS) team of engineering specialists was formed by the Structural Engineering Institute of the American Society of Civil Engineers (SEI/ASCE) and Federal Emergency Management Agency (FEMA). The BPS team issued its report in May 2002, finding that the aircraft impacts caused "extensive structural damage, including localized collapse" and that the resulting fires "further weakened the steel-framed structures, eventually leading to total collapse." They