On the morning of September 11, 2001, 19 men hijacked four U.S. commercial airplanes that had taken off with full fuel tanks for the West Coast. The hijackers deliberately crashed the planes into the Twin Towers of the World Trade Center, the Pentagon and onto a field outside of Shanksville, Pennsylvania. The losses were devastating: A total of 2,977 people were killed in New York City, Washington, D.C. and Pennsylvania.

Watch HISTORY videos below about the devastating attacks on that day and the aftermath.

Remembering 9/11: The Photo Archive

9/11 Timeline

Remembering 9/11: The Elevator Motor

The 9/11 Flag: Lost and Found

Remembering 9/11: The Ground Zero Cross

Remembering 9/11: The Ground Zero Bible

Remembering 9/11: Karyn's Wings

Remembering 9/11: Pentagon Employee Bruce Powers

The 9/11 Survivor Tree

"9/11: Inside Air Force One" premieres Wednesday, September 11 at 9/8c.