8:45 a.m. (all times are EDT):

A hijacked passenger jet, American Airlines Flight 11 out of Boston, Massachusetts, crashes into the north tower of the World Trade Center, Tearing a gaping hole in the building and setting it afire.

9:03 a.m.:

A second hijacked airliner, United Airlines Flight 175 from Boston, Crashes into the south tower of the World Trade Center and explodes. Both buildings are burning.

9:17 a.m.:

The Federal Aviation Administration Shuts down all New York City area airports.

9:21 a.m.:

The Port Authority of New York and New Jersey orders All bridges and tunnels in the New York area closed.

9:30 a.m.:

President Bush, speaking in Sarasota, Florida, Says the country has suffered an "apparent terrorist attack."

9:40 a.m.:

The FAA halts all flight operations at U.S. airports, The first time in U.S. history that air traffic nationwide has been halted.

9:43 a.m.:

American Airlines Flight 77 crashes into the Pentagon, Sending up a huge plume of smoke. Evacuation begins immediately.

9:45 a.m.:

The White House evacuates.

9:57 a.m.:

Bush departs from Florida.

10:05 a.m.:

The south tower of the World Trade Center collapses, plummeting into the streets below. A massive cloud of dust and debris forms and slowly drifts away from the building.

10:08 a.m.:

Secret Service agents armed with automatic rifles are deployed Into Lafayette Park across from the White House.

10:10 a.m.:

A portion of the Pentagon collapses.

10:10 a.m.:

United Airlines Flight 93, also hijacked, crashes in Somerset County, Pennsylvania, southeast of Pittsburgh.

10:13 a.m.:

The United Nations building evacuates, including 4,700 people from the headquarters building And 7,000 total from UNICEF and U.N. development programs.

10:22 a.m.:

In Washington, the State and Justice departments are evacuated, Along with the World Bank.

10:24 a.m.:

The FAA reports that all inbound transatlantic aircraft flying into the United States are being diverted to Canada.

10:28 a.m.:

The World Trade Center's north tower collapses from the top down As if it were being peeled apart, Releasing a tremendous cloud of debris and smoke.

10:45 a.m.:

All federal office buildings in Washington are evacuated.

10:57 a.m.:

New York Gov. George Pataki says all state government offices are closed.

11:18 a.m.:

American Airlines reports it has lost two aircraft. American Flight 11, a Boeing 767 flying from Boston to Los Angeles, had 81 passengers and 11 crew aboard. Flight 77, a Boeing 757 en route from Washington's Dulles International Airport to Los Angeles, had 58 passengers and six crew members aboard. Flight 11 slammed into the north tower of the World Trade Center. Flight 77 hit the Pentagon.

11:26 a.m.:

United Airlines reports that United Flight 93, en route from Newark, New Jersey, To San Francisco, California, has crashed in Pennsylvania. The airline also says that it is "deeply concerned" about United Flight 175.

11:59 a.m.:

United Airlines confirms that Flight 175, from Boston to Los Angeles, Has crashed with 56 passengers and nine crew members aboard. It hit the World Trade Center's south tower.

Second tower falls.

12:15 p.m.:

The Immigration and Naturalization Service says U.S. borders with Canada and Mexico Are on the highest state of alert, But no decision has been made about closing borders.

1:04 p.m.:

Bush, speaking from Barksdale Air Force Base in Louisiana, Says that all appropriate security measures are being taken, Including putting the U.S. military on high alert worldwide. He asks for prayers for those killed or wounded in the attacks and says, "Make no mistake, the United States will hunt down and punish those responsible for these cowardly acts."

1:27 p.m.:

A state of emergency is declared by the city of Washington