Nearly 3,000 people lost their lives in the tragedy.
Sixteen years after the Sept. 11 attacks on America in 2001, the nation is remembering that fateful day and how it unfolded on live television.
It was a clear, sunny Tuesday morning when al-Qaeda terrorists hijacked four passenger planes, with the first striking the north tower of the World Trade Center just before 9 a.m.
As news cameras and stations broke into the events unfolding in lower Manhattan, a second plane flew into the south tower just minutes later, at 9:03 a.m. before an audience of horrified viewers.
Then-president George W. Bush was visiting a second grade class at Emma E. Booker Elementary School in Sarasota, Fla., that morning when he was informed of the events in New York by adviser Andy Card.
At 9:30 a.m., Bush addressed the nation from the school.
“Terrorism against our nation will not stand,” he defiantly said in his speech.
Not long after his remarks, a third hijacked airliner flew into the Pentagon in Washington, D.C., prompting the evacuation of all government buildings in the area.
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In Manhattan, all bridges and tunnels were closed to traffic.
At 9:59 a.m., as the world was still processing what was happening in Washington and New York City, the south tower of the World Trade Center collapsed live on TV. A half hour later, the North Tower followed, changing New York City's iconic skyline forever.
A short time later, passengers on a fourth aircraft fought back against the terrorists who had taken the plane. A struggle in the cockpit led the plane to crash into a field in Shanksville, Pa., killing everyone on board.
That plane's intended target was said to have been the Capitol Building in D.C.
Nearly 3,000 people lost their lives in Manhattan, the nation's capital and in Shanksville.
Each year, families of the victims of Sept. 11 gather at the site of the World Trade Center to honor the lives lost on that fateful day by reading the names of the office workers and first responders who perished.
Watch Below: National Anthem Performed at the 9/11 Museum and Memorial on Sept. 11, 2017
