The deadliest aviation-related disaster of any kind, considering fatalities on both the aircraft and the ground, was the destruction of the World Trade Center in New York City on September 11, 2001. On that morning, four commercial aircraft traveling on transcontinental flights from East Coast airports to California were hijacked after takeoff. The four hijacked aircraft were subsequently crashed in four separate suicide attacks against major American landmarks, by 19 Islamic terrorists affiliated with Al Qaeda. American Airlines Flight 11 and United Airlines Flight 175 were intentionally crashed into the North and South Towers respectively of the World Trade Center, destroying both buildings in less than two hours. The World Trade Center crashes killed 2,753, the vast majority of fatalities being occupants of the World Trade Center towers or emergency personnel responding to the disaster. Also, 184 were killed by American Airlines Flight 77, which crashed into the Pentagon (causing severe damage and partial destruction to the building's west side). 40 passengers were also killed when United Airlines Flight 93 crashed into a Somerset County, Pennsylvania field after passengers fought back and prevented the hijackers from reaching their designated target.
Early on the morning of September 11, 2001, 19 hijackers took control of four commercial airliners (two Boeing 757s and two Boeing 767s) en route to California (three headed to LAX in Los Angeles and one to SFO in San Francisco).
On September 14, 2001, the U.S. Congress passed the Authorization for Use of Military Force Against Terrorists. Still in effect, it grants the President the authority to use all "necessary and appropriate force" against those whom he determined "planned, authorized, committed or aided" the September 11 attacks, or who harbored said persons or groups.
There were reports of attacks on mosques and other religious buildings (including the firebombing of a Hindu temple), and assaults on people, including one murder: Balbir Singh Sodhi, a Sikh mistaken for a Muslim, was fatally shot on September 15, 2001, in Mesa, Arizona.
Shortly after the attacks, President Bush made a public appearance at Washington, D.C.'s largest Islamic Center and acknowledged the "incredibly valuable contribution" that millions of American Muslims made to their country and called for them "to be treated with respect.".
On September 20, 2001, President George W. Bush addressed the nation and a joint session of the United States Congress regarding the events of September 11 and the subsequent nine days of rescue and recovery efforts, and described his intended response to the attacks. New York City mayor Rudy Giuliani's highly visible role won him high praise in New York and nationally.
On September 27, 2001, FBI released photos of all 19 hijackers, along with information about possible nationalities and aliases. Fifteen of the men were from Saudi Arabia, two from the United Arab Emirates, one from Egypt, and one from Lebanon.