8:46 a.m.: Hijackers deliberately crash American Airlines Flight 11 into floors 93 through 99 of the North Tower (1 WTC).

9:03 a.m.: Hijackers deliberately crash United Airlines Flight 175 into floors 77 through 85 of the South Tower (2 WTC).

9:37 a.m.: Hijackers deliberately crash American Airlines Flight 77 into the Pentagon, near Washington, D.C.

9:59 a.m.: The South Tower (2 WTC) collapses.

10:03 a.m.: After learning of the other attacks, passengers on United Airlines Flight 93 launch a counterattack on hijackers aboard their plane to try to seize control of the aircraft. In response, the hijackers crash the plane into an empty field near Shanksville, Pennsylvania.

10:28 a.m.: The North Tower (1 WTC) collapses. The 16-acre World Trade Center site is in ruins, with collateral damage affecting all adjacent properties and streets. A rescue and recovery effort begins immediately.