into the world trade center. that crash killing everyone on board, severing emergency stairwells, trapping hundreds of people on the top floors of the tower. by this point, united airlines flight 175 also originating from boston had been hijacked. at 9:03 a.m. with 65 people on board, flight 175 hits the south tower of the world trade center. >> i've never seen anything like it. >> shortly after that second crash, president george w. bush is informed that america is under attack. at 9:37 a.m., american airlines flight 77 crashes into the pentagon. >> we are looking at live pictures of the pentagon where there is billowing smoke. >> reporter: the crash killing 58 passengers, including the hijackers, along with six crew members. 125 military and civilian personnel would also die in the crash and the fire that followed. back in new york at 9:59 a.m. after burning for nearly an hour, the south tower collapses.