Timeline for 9/11
8:45 a.m.: Jet airliner crashes into the north tower of the World Trade Center in New York.
9:03 a.m.: A second airliner crashes into its twin south tower, causing a devastating explosion.
9:10 a.m.: President Bush, in Sarasota, Florida, is reading to children in a classroom when his chief of staff, Andrew Card, whispers news of the attacks into his ear.
9:20 a.m.: American Airlines says one of the planes that crashed into the Trade Center was American Airlines Flight 11, hijacked after takeoff from Boston en route to Los Angeles. The FBI investigates reports of planes being hijacked before the World Trade Center crashes.
9:29 a.m.: First reports of casualties indicate that at least six people were killed, with at least 1,000 injured.
9:30 a.m.: President Bush declares: "We have had a national tragedy. Two airplanes have crashed into the World Trade Center in an apparent terrorist attack on our country."
9:43 a.m.: Abu Dhabi television reports it received a call from the Democratic Front for the Liberation of Palestine, claiming responsibility for crashing two planes into the WTC. However, leading officials later deny the claim. Senior law enforcement officials say car bomb explodes outside of State Department in Washington, D.C. Federal protective services later denies car bomb attack occurred.
9:43 a.m.: Another plane crashes into the Pentagon in Washington. The nerve center of the U.S. military bursts into flames and a portion of one side of the five-sided structure collapses.
9:48 a.m.: Government buildings in Washington, including the White House and the Capitol are evacuated with officials citing a credible threat of a terrorist attack. Authorities across the country go on alert, tightening security at strategic facilities and evacuating high-profile buildings. US monuments and museums in Washington D.C. are closed.
9:49 a.m.: The Federal Aviation Administration shuts down all airports across the U.S. Financial markets suspend trading in the wake of the attacks.
10:00 a.m.: Officials at Somerset County Airport say United Airlines Flight 93, en route from Newark, N.J., to San Francisco, crashes in western Pennsylvania, about 80 miles southeast of Pittsburgh. The crash site is 85 miles northwest of Camp David.
10:05 a.m.: The south tower of the World Trade Center collapses.
10:29 a.m.: The north tower of the World Trade Center collapses.
12:33 p.m.: United Airlines confirms a second of its planes has crashed at an unknown location.
12:39 p.m.: Flown to Barksdale Air Force Base near Shreveport, Louisiana, President Bush makes a second statement, vowing to hunt down and punish those responsible.
2:48 p.m.: New York Mayor Rudy Giuliani says the eventual death toll from Tuesday's attack may be "more than any of us can bear."
2:51 p.m.: The Navy dispatches missile destroyers and other equipment to New York and Washington.
4:25 p.m.: Securities and Exchange Commission says all financial markets are closed for the day. The American Stock Exchange, the Nasdaq and the New York Stock Exchange say they will remain closed on Wednesday.
4:30 p.m.: President Bush leaves Offutt Air Force Base in Nebraska aboard Air Force One to return to Washington, where he will make a nationally televised address.
5:25 p.m.: World Trade Center 7 collapses.
8:30 p.m.: President Bush addresses the nation. "These acts of mass murder were intended to frighten our nation into chaos and retreat," he said. "But they have failed; our country is strong."
8:35 p.m.: President Bush attends national security meeting.