Nineteen terrorists hijack four airliners in the eastern United States.
Two planes crash into the World Trade Center in New York City, one in each tower. Both towers completely collapse, due to the intense flames.
One plane crashes into the Pentagon.
One plane crashes in central Pennsylvania after a passenger rebellion. It was thought to have been targeted for Camp David, Maryland, the Capitol building, or the White House.
All air traffic is grounded and all airports closed across the United States; international flights are diverted to Canada. Financial markets are closed.
U.S. skyscrapers and most government and public complexes are evacuated, and American armed forces worldwide are placed on high alert.
The prime suspect is Osama bin Laden, who denies involvement.