9:59:04 a.m.: The south tower of the World Trade Center collapses, plummeting into the streets below

9:47 a.m.: Commanders worldwide ordered to raise threat alert status four notches to "Delta", the highest level, to defend United States.

9:37 a.m.: American Airlines Flight 77 is lost from radar screens and impacts the western side of the Pentagon.

9:30 a m.: Bush, speaking from Emma E. Booker Elementary in Sarasota, Florida, says the country has suffered an "apparent terrorist attack"

9:05 a.m.: Andrew Card walks up to Bush and whispers in his ear "A second plane has hit the World Trade Center. America is under attack."

September 11th Timeline: 9:02:54 a.m.: United Airlines Flight 175 impacts the south side of the South Tower of the WTC

September 11th Timeline: 8:46:26 a.m.: American Airlines Flight 11 impacts the north side of the North Tower (1 World Trade Center)