September 11, 2001: Members of the Al-Qaeda network steered two passenger jets into the twin towers of New York's World Trade Center, causing them to collapse. A third aircraft hit the Pentagon in Washington and a fourth hijacked plane crashed in Pennsylvania. Nearly 3,000 people died in the attacks, the worst on US soil.

A deadly blast rocked the World Trade Center after two airplanes crashed into it on September 11, 2001 (Pic - AFP)