Notes

When Boeing jets piloted by terrorists struck the Twin Towers, some 10,000 gallons (38 kiloliters) of jet fuel fed an enormous fireball. But, the impact of the planes and the burst of flames did not make the Towers collapse right away. Like most buildings, the Twin Towers had redundant design, which means that when one system fails, another carries the load. Each of the Twin Towers had 244 columns around a central core that housed the elevators, stairwells, mechanical systems, and utilities. When some columns were damaged, others could still support the building.The impact of the aircraft and other flying objects (1) scraped off insulation that protected the steel from high temperatures; (2) damaged the sprinkler system of the building; (3) sliced and cut many of the interior columns and damaged others; and (4) shifted and redistributed the building load among columns that were not immediately damageduld still support the buildingThere were 2,595 people in the World Trade Center and near it, including: 343 NYFD firefighters and paramedics 23 NYPD police officers 37 Port Authority police officers 1,402 people in Tower 1 614 people in Tower 2 658 people at one company, Cantor Fitzgerald 1,762 New York residents 674 New Jersey residents 1 NYFD firefighter killed by a man jumping off the top floors of the Twin Towers...