At 9: 59 a. m. ET on Sept. 11, 2001, the South Tower collapsed at the World Trade Center in New York City during a series of terrorist attacks that changed the U. S. forever. At 10: 03 a. m. ET, the passengers on United Airlines Flight 93 launched a counterattack on the hijackers aboard their plane, causing a crash into a field near Shanksville, Pennsylvania.
It's believed the aircraft may have been headed toward Washington, D. C.