WTC 9/11

The September 11 attacks (also referred to as September 11, September 11th or 9/11) were a series of four coordinated suicide attacks that were committed in the United States on September 11, 2001, striking the areas of New York City and Washington, D.C. On that Tuesday morning, 19 terrorists from the Islamist militant group Al-Qaeda hijacked four passenger jets. The hijackers intentionally piloted two of those planes, American Airlines Flight 11 and United Airlines Flight 175, into the Twin Towers of the World Trade Center complex in New York City; both towers collapsed within two hours. The hijackers also intentionally crashed American Airlines Flight 77 into the Pentagon in Arlington, Virginia, and intended to pilot the fourth hijacked jet, United Airlines Flight 93, into a target in Washington, D.C.; however, the plane crashed into a field near Shanksville, Pennsylvania after its passengers attempted to take control of the jet from the hijackers. Nearly 3,000 people died in the attacks.

The term ground zero (sometimes also known as surface zero as distinguished from zero point) describes the point on the Earth's surface closest to a detonation. In the case of an explosion above the ground, ground zero refers to the point on the ground directly below the detonation (see hypocenter).

The term has often been associated with nuclear explosions and other large bombs, but is also used in relation to earthquakes, epidemics and other disasters to mark the point of the most severe damage or destruction. The term is often re-used for disasters that have a geographic or conceptual epicenter.