9/11 Anniversary: Harrowing Pictures That Capture America's Deadliest Terror Attack

On September 11, in the year 2001, four coordinated terrorist attacks were carried out by the Islamic terrorist group al-Qaeda against the United States on the morning of Tuesday. In this file photo taken on September 11, 2001, smoke billowing after the first of the two towers of the World Trade Center collapses in New York City. (Photo by HENNY RAY ABRAMS / AFP)

New York City continues to count people with cancer and other serious diseases, including lung disease, linked to the toxic cloud that hovered for weeks on the tip of Manhattan. (Photo by DOUG KANTER / AFP)