NEW YORK - SEPTEMBER 11: The World Trade Center is engulfed in flames just before the south tower collapsed September 11, 2001 in New York City. (Photo by Thomas Nilsson/ Getty Images)
NEW YORK - SEPTEMBER 11: The World Trade Center is engulfed in flames just before the south tower collapsed September 11, 2001 in New York City. (Photo by Thomas Nilsson/ Getty Images)