The sequence of events related to the terrorist attacks on 9/11 were as follows (all times are eastern daylight time):

• 8:46 A.M.: A passenger plane crashes into the north tower of New York City’s World Trade Center. At first it is assumed to be an accident. But within hours, it is learned that the plane was American Airlines Flight 11, and commandeered by hijackers shortly after takeoff from Boston headed to Los Angeles; it carried 81 passengers (including 5 hijackers) and 11 crewmembers.

• 9:03 A.M.: A second passenger plane slams into the south tower of the World Trade Center and explodes. United Airlines later announces that this was Flight 175, another Boston-Los Angeles plane; it carried 56 passengers (including 5 hijackers) and 9 crewmembers. Both towers of the World Trade Center are in flames.

• 9:21 A.M.: Bridges and tunnels leading into New York City are closed. Within the hour, Mayor Rudolph Giuliani (1944-) orders an evacuation of Manhattan south of Canal Street.

• 9:25 A.M.: All flights in the United States are grounded. It is the first time in history that the Federal Airlines Administration (FAA) halts all flights.

• 9:30 A.M.: President George W. Bush (1946-), scheduled to speak at a grade school in Sarasota, Florida, remarks that the nation has been the target of an “apparent terrorist attack.”

• 9:45 A.M.: A third passenger plane crashes into the east wall of the Pentagon in Arlington, Virginia. The plane was American Airlines Flight 77, carrying 58 passengers (including 5 hijackers) and 6 crewmembers. It originated at Washington, D.C.’s Dulles International Airport and was headed to Los Angeles. After being hijacked, the plane made a u-turn over the Ohio-Kentucky border to return to the Washington, D.C.-area, where it hit its intended target.

• 9:45 A.M.: The White House is evacuated.

• 10:05 A.M.: The south tower of the World Trade Center collapses.

• 10:10 A.M.: A large section of the Pentagon collapses.

• 10:10 A.M.: A fourth passenger plane crashes in a field in Somerset County, in southwestern Pennsylvania (outside of Pittsburgh). It was United Airlines Flight 93, originating in Newark, New Jersey, and bound for San Francisco. After being hijacked, the plane made a u-turn over Ohio and was headed for a target in Washington, D.C. (later thought to be Camp David, the White House, or the U.S. Capitol building). After learning via cell phones of the other hijackings, a group of passengers stormed the cockpit in an effort to take the plane, which crashed in the countryside. The plane carried 37 passengers (including 4 hijackers) and a crew of 7. There were no survivors.

• 10:24 A.M.: The FAA reports that it has diverted all incoming transatlantic flights to Canada.

• 10:28 A.M.: The north tower of the World Trade Center falls. The collapse of each tower blankets lower Manhattan in smoke and ash, turning the brilliantly sunny day to darkness.

• 10:45 A.M.: All federal office buildings in the nation’s capital are evacuated.

• 2:00 P.M.: Senior FBI sources reveal to the media that they are working under the assumption that the four airplanes that crashed were part of a terrorist attack. The FBI later learns the identities of all 19 hijackers (there were 5 on board each plane, except Flight 93, which had 4).

• 4:00 P.M.: Media reports indicate that U.S. officials have credible evidence tying the morning’s attacks to Saudi militant Osama bin Laden (1957-).

• 5:20 P.M.: Building 7 (a 47-story structure) of the World Trade Center complex collapses. Nearby buildings are in flames.