The major event that took place on September 11, 2001, was a series of terrorist attacks carried out by the Islamist extremist group al-Qaeda. Coordinated attacks included the hijacking of commercial airplanes, with two crashing into the World Trade Center towers in New York City, one striking the Pentagon, and another crashing in Pennsylvania after passengers intervened. This catastrophic event resulted in approximately 3,000 deaths and caused widespread devastation. In its wake, the U.S. altered its foreign policy significantly, launching the War on Terror, which included military operations in Afghanistan and heightened security measures domestically and internationally.