In a horrific sequence of destruction, commercial jetliners hijacked by terrorists crashed two planes into the World Trade Center in New York City and another into the Pentagon in Washington, D.C. A fourth plane crashed in Western Pennsylvania. PHOTO ESSAYS ATTACK ON NEW YORK CITY ATTACK ON WASHINGTON, D.C. CRASH IN PENNSYLVANIA
Smoke billows from lower Manhattan in New York, where the Twin Towers once stood. (AP Photo)