9/11 Timeline-- Part 5: Flight 93, Collapse of the North Tower and the Seven World Trade Center Building

All times are Eastern.

**  10:07 am:  After passengers and crew members aboard the hijacked Flight 93 contact friends and family and learn about the attacks on New York and Washington, D.C., they mount an attempt to retake the plane.  In response, the hijackers deliberately crash the plane into a field in Somerset County, Pennsylvania., killing all 40 passengers and crew aboard.

**  10:28 am:  The World Trade Center's North Tower collapses, 102 minutes after being struck by Flight 11.

**  11 am:  New York Mayor Rudolph Giuliani calls for the evacuation of Lower Manhattan south of Canal Street, including more than one million residents,  workers and tourists, as efforts continue throughout the afternoon to search for survivors.

**  1 pm;  At Barksdale Air Force Base in Louisiana, President Bush announces that U.S. forces are on high alert throughout the world.

**  2:51 pm:  The U.S. Navy dispatches missile destroyers to New York and Washington, D.C.

**  5:20 pm:  The 47-story Seven World Trade Center building collapses after burning for hours; the building had been evacuated in the morning, and there are no casualties., though the collapse forces rescue workers to flee for their lives.

A Sad Day in U.S. history.