What happen on sep 11 2001?

On September 11, 2001, a series of coordinated terrorist attacks were carried out by the extremist group al-Qaeda against the United States. Four commercial airplanes were hijacked; two were flown into the Twin Towers of the World Trade Center in New York City, causing both towers to collapse, while a third plane struck the Pentagon in Arlington, Virginia. The fourth plane, United Airlines Flight 93, was headed for a target in Washington, D.C., but passengers attempted to retake control, leading it to crash in a field in Pennsylvania. Nearly 3,000 people lost their lives, and the attacks prompted significant changes in U.S. domestic and foreign policy, including the initiation of the War on Terror.