At 9:45, the FAA commands all aircraft already in the skies to land as soon as possible. That means air traffic controllers must somehow coordinate the unscheduled, and unprecedented, landing of nearly 4,500 planes.
At 10:05 a.m., the enormity of the attacks becomes much clearer as the South Tower of the World Trade Center collapses. Five minutes later, part of the Pentagon caves in as well.
At the same time, passengers aboard Flight 93, having learned of the other attacks via cell phones, attempt to wrest control of the plane from the hijackers, who crash the plane into a field in Pennsylvania. It's the only plane to have missed its target, which was presumably the U.S. Capitol.
At 10:28 a.m., with the now fully alert world watching on television, the North Tower of the World Trade Center comes crashing down. Now-iconic video footage and still photos capture many events of the day, from the planes hitting the towers to the billowing aftermath of their collapse into the streets of the city.
Although it's not even noon yet, all 19 hijackers are already dead, along with thousands of American victims, and a new era in history has begun.
At 8:30 p.m. on the evening of September 11, President Bush addresses the people of the United States and asserts that the country will win the war on terrorism.