9:03 a.m.: United Airlines Flight 175, a Boeing 767, crashes into the second World Trade Center tower and explodes.
9:17 a.m.: FAA shuts down all New York City area airports.
9:30 a.m.: In a speech from Florida, President George Bush says the country has suffered an "apparent terrorist attack."
9:40 a.m.: FAA halts all flight operations at U.S. airports.
9:43 a.m.: American Airlines Flight 77, a Boeing 757, crashes into the Pentagon. The building is evacuated immediately.
9:45 a.m.: White House evacuates.
10:05 a.m.: South tower of the World Trade Center collapses.
10:10 a.m.: Portion of the Pentagon collapses.
10:10 a.m.: United Airlines Flight 93, a Boeing 757, crashes in Somerset County, Pennsylvania, southeast of Pittsburgh.
10:28 a.m.: The World Trade Center's north tower collapses
10:45 a.m.: All federal office buildings in Washington are evacuated.
4:10 p.m.: Building 7 of the World Trade Center complex is reported on fire.
5:20 p.m.: The 47-story Building 7 of the World Trade Center complex collapses.