- 9:03 AM: As news cameras continue to monitor the World Trade Center towers, a second aircraft crashes into the side of the southern tower.
- 9:17 AM: The FAA shuts down all New York City airports.
- 9:40 AM: For the first time in history, the FAA shuts down all air traffic nationwide.
- 9:43 AM: A third aircraft crashes outside the Pentagon in Washington, D.C., filling the building with smoke and prompting immediate evacuation.
- 10:05 AM: Still on live television, the south tower of the World Trade Center collapses from the top down.
- 10:28 AM: The north tower of the World Trade Center collapses from the top down. Half of Manhattan is covered in ash, soot and black smoke.
- 11:18 AM: Confirmations from the airlines begin to arrive. At least four planes were hijacked after leaving different east coast airports that morning. American Airlines Flight 11, one of the planes that hit the World Trade Center, was a Boeing 767 leaving Boston for Los Angeles; it had 92 passengers and crew aboard. American Airlines Flight 77, a Boeing 757 leaving Washington, D.C. for Los Angeles, had 64 passengers and crew aboard.
- 11:26 AM: United Airlines confirms that Flight 93 from Newark to San Francisco had crashed in Pennsylvania.
- 11:59 AM: United Airlines confirms that Flight 175 from Boston to Los Angeles had crashed in New York City with 65 passengers and crew aboard.
Timeline information obtained from CNN.com and other news sources