September 11, 2001: 2,977 lives were lost in a day during the worst terror attack on US soil

On September 11, 2001, a total of 19 terrorists hijacked four airplanes, crashing two of them into the World Trade Center, one into the Pentagon and the fourth into a Pennsylvania field, killing thousands of Americans in the process and wreaking destruction that, in its aftermath, has continued to claim lives.

Never forget: A timeline of the events of September 11, 2001

On September 11, 2001, more than 2,600 people perished at the World Trade Center, 125 people died at the Pentagon and 256 people died on four airplanes after terrorists hijacked the planes and turned them into guided missiles.

Memorial Stair Climb held in Dallas to remember 9/11 first responders

Wednesday marks the 18th anniversary of the September 11th attacks, and people around the world are remembering the first responders who made the ultimate sacrifice on 9/11.