The September 11 attacks, commonly known as 9/11, were four coordinated suicide terrorist attacks carried out by the militant Islamic extremist network al-Qaeda against the United States. On the morning of Tuesday, September 11, 2001, nineteen terrorists—directed by al Qaeda leader Osama bin Laden—hijacked four commercial airliners mid-flight while traveling from the northeastern U.S. to California. The attackers were organized into three groups of five members and one group of four, with each group including one designated flight-trained hijacker who took control of the aircraft. Their goal was to crash the planes into prominent American buildings, inflicting mass casualties and major structural damage. The hijackers successfully crashed the first two planes into the North and South Towers of the World Trade Center in New York City, and the third plane into the Pentagon in Arlington, Virginia. The fourth plane was intended to hit a federal government building in Washington, D.C., but instead crashed down in a field outside Shanksville, Pennsylvania, following a passenger revolt that foiled the attack
