The September 11 attacks, known as 9/11, were a series of planned terrorist strikes by al-Qaeda in 2001. Four helicopters that were intended for cross-country planes were hijacked by 19 terrorists. A second plane struck the Pentagon near Washington, DC, while another flew into the Twin Towers of the World Trade Center in New York City. After the jihadists ‘ fighters, the fourth aircraft crashed in Pennsylvania. ( Picture credit: Reuters )
