A wide-ranging assault, including hijackings and bombings, has hit the United States, concentrated mostly in New York City and Washington, D.C. Here is a chronology of the major events as they unfolded.
8:50 a.m. ET (approximately): The first plane (American Airlines Flight 11, a Boeing 767 with 81 passengers, 9 flight attendants and 2 pilots aboard, headed from Boston to Los Angeles) crashes into One World Trade Center, the northernmost of the twin towers.
9 a.m. ET (approximately): A second plane (United Airlines Flight 175, a Boeing 767 headed from Boston to Los Angeles with 56 passengers, 7 flight attendants and 2 pilots) strikes Two World Trade Center, the southernmost of the twin towers.
9:25 a.m. ET: The New York Stock Exchange, Mercantile Exchange and financial district are evacuated, and trading is suspended.
9:38 a.m. ET: American Airlines Flight 77, a Boeing 757 with 58 passengers 4 flight attendants and 2 pilots, heading from Washington, D.C., to Los Angeles, crashes into the west side of the Pentagon, where about 20,000 people work, including most of the nation's highest-ranking military officials.
9:50 a.m. ET: The Federal Aviation Administration reports all flights nationwide are grounded.
10:09 a.m. ET: Two World Trade Center (the southernmost tower) collapses.
10:16 a.m. ET: A portion of the Pentagon collapses after a passenger plane crashes into it.
10:20 a.m. ET: All federal buildings nationwide are ordered evacuated.
10:26 a.m. ET: Most inbound international inbound flights rerouted.
10:30 a.m. ET: One World Trade Center (the northernmost tower) collapses.
10:30 a.m. ET: Gov. George Pataki declares a state of emergency in New York state and asked the president to declare New York City a federal disaster area.
10:35 a.m. ET: Washington and all New York City area airports closed completely.
10:42 a.m. ET: United Airlines Flight 93, a Boeing 757 with 45 people aboard headed from Newark, N.J., to San Francisco, crashes in Somerset County, Pa.
10:44 a.m. ET: New York mayoral primary canceled.
10:50 a.m. ET: All museums and monuments in Washington, D.C., closed.
11:08 a.m. ET: Canada shuts down all airports.
12:30 p.m. ET: New York City Mayor Rudolph Giuliani says subways are operating outside of Manhattan, not inside.