United States invasion of Afghanistan
On the morning of 11 September 2001, al-Qaeda carried out four coordinated attacks on the United States. Four commercial passenger jet airliners were hijacked. The hijackers – members of al-Qaeda's Hamburg cell – intentionally crashed two of the airliners into the Twin Towers of the World Trade Center in New York City. Both buildings collapsed within two hours from fire damage related to the crashes, destroying nearby buildings and damaging others. The hijackers crashed a third airliner into the Pentagon in Arlington County, Virginia. The fourth plane crashed into a field near Shanksville, Pennsylvania, after some of its passengers and flight crew attempted to retake control of the plane, which the hijackers had redirected toward Washington, D.C., to target the White House or the United States Capitol. No flights had survivors. In total, 2,996 people, including the 19 hijackers, died and more than 6,000 others injured in the attacks. According to the New York State Health Department, 836 first responders, including firefighters and police personnel, had died as of June 2009.
American Airlines Flight 77
On the morning of September 11, 2001, the five hijackers arrived at Washington Dulles International Airport. At 07:15, Khalid al-Mihdhar and Majed Moqed checked in at the American Airlines ticket counter for Flight 77, arriving at the passenger security checkpoint a few minutes later at 07:18. Both men set off the metal detector and were put through secondary screening. Moqed continued to set off the alarm, so he was searched with a hand wand. The Hazmi brothers checked in together at the ticket counter at 07:29.[Hani Hanjour checked in separately and arrived at the passenger security checkpoint at 07:35. Hanjour was followed minutes later at the checkpoint by Salem and Nawaf al-Hazmi, who also set off the metal detector's alarm. The screener at the checkpoint never resolved what set off the alarm. As seen in security footage later released, Nawaf Hazmi appeared to have an unidentified item in his back pocket. Utility knives up to four inches were permitted at the time by the Federal Aviation Administration (FAA) as carry-on items. The passenger security checkpoint at Dulles International Airport was operated by Argenbright Security, under contract with United Airlines.