Photo gallery: September 11, 2001
A fiery blast rocks the south tower of the World Trade Center as the hijacked United Airlines Flight 175 from Boston crashes into the building Sept. 11, 2001, in New York City.
(Spencer Platt / Getty Images)Chicago Tribune
On a brilliant, sunny Tuesday morning, Sept. 11, 2001, the United States shifted from a nation vaguely concerned about its enemies around the world to a nation ready to declare war on terrorists and on the countries that house and support them.
(Richard Drew / Associated Press)
(Spencer Platt / Getty Images)
(Amy Sancetta / Associated Press)
(Doug Mills / Associated Press)
(Stan Honda / AFP-Getty Image)
(Mario Tama / Getty Images)
People flee the scene near New York’s World Trade Center after terrorists crashed two planes into the twin towers on Sept. 11, 2001.
(Diane Bondareff / Associated Press)(Marty Lederhandler / Associated Press)
Two women hold each other as they watch the World Trade Center burn after a terrorist attack on the twin skyscrapers in New York on Sept. 11, 2001.
(Ernesto Mora / Associated Press)People run from the collapse of the World Trade Center in New York on Sept. 11, 2001.
(Suzanne Plunkett / Associated Press)