World Trade Center and Pentagon attacked on Sept. 11, 2001

 NEW YORK —  

In the worst terrorist attack ever against the United States, hijackers struck at the preeminent symbols of the nation’s wealth and might Tuesday, flying airliners into the World Trade Center and the Pentagon and killing or injuring thousands of people.

As a horrified nation watched on television, the twin towers of the World Trade Center in lower Manhattan collapsed into flaming rubble after two Boeing 767s rammed their upper stories. A third airliner, a Boeing 757, flattened one of the Pentagon’s five sides.

A fourth jetliner crashed in western Pennsylvania. Authorities said the hijackers might have been trying to aim the plane at the presidential retreat at Camp David, Md., the Capitol or other targets in Washington.