Science Fair Project Encyclopedia September 11, 2001 attacks The
September 11, 2001 attacks were a series of coordinated
terrorist attacks carried out in the United States on September
11, 2001. Nineteen people affiliated to the al-Qaeda network, a
militant Islamist organization, hijacked four commercial
aircraft. They crashed one into each of the two tallest towers
of the World Trade Center in Manhattan, New York City, shortly
after which both towers collapsed. The third aircraft crashed
into the U.S. Department of Defense headquarters, the Pentagon,
in Arlington County, Virginia, just outside the capital,
Washington, D.C.. The fourth plane crashed into a field near
Shanksville, Pennsylvania following a passenger rebellion. The
attacks were the most lethal ever carried out in the U.S., and
the first upon the mainland since the Japanese fire balloons of
November 1944. The death toll of 2,986 exceeded the toll of
approximately 2,400 dead after the surprise Japanese attack on
Pearl Harbor on December 7, 1941. T