1. On September 11, 2001, 19 al-Qaeda-trained terrorists hijacked four U.S. commercial airliners. The hijackers crashed two of the jets into the World Trade Center towers in New York City and crashed the third jet into the Pentagon outside Washington, D.C. Passengers and crew battled the hijackers for control of the fourth jet, and it crashed into a field near Shanksville, Pennsylvania, short of reaching the hijackers' intended target in Washington, D.C.

2. The attacks caused the subsequent collapse of the World Trade Center twin towers, damaged the Pentagon, and killed approximately 3,000 people. Included in the death toll were hundreds of firefighters and rescue personnel who responded to the crashes at the World Trade Center site and who were in the process of rescuing those inside when the buildings collapsed. 3. The September 11, 2001 attacks were the most deadly international terrorist attack in history and the largest attack on United States territory since the Japanese attack on Pearl Harbor on December 7, 1941. http://hnn.us/article/874 4. "I have a sense it's a horrendous number of lives lost. Right now we have to focus on saving as many lives as possible. - Mayor Rudolph W. Giuliani. "These acts of mass murder were intended to frighten our nation into chaos and retreat, but they have failed," -a somber president told the nation in an address from the Oval Office shortly after 8:30 p.m 5. Conrad Quilty-Harper 6. The evacuation of the North Tower proceeded efficiently from the time it was hit, via the three stairways. The elevators were all knocked out. The 102 minutes between the impact and collapse allowed the vast majority of its occupants below the crash zone to escape to safety 7. In a few locations, we came across golf carts that were still running. It was apparent that these common modes of transportation around the Pentagon on this day became escape vehicles. After exhausting our breathing apparatus, we were physically and mentally drained. We returned to the outside and immediately refilled our bottles. -http://pentagon.spacelist.org/ 8. The 9/11 attacks on the World Trade Center and the Pentagon were far more elaborate, precise, and destructive than any of these earlier assaults. But by September 2001, the executive branch of the U.S. government, the Congress, the news media, and the American public had received clear warning that Islamist terrorists meant to kill Americans in high numbers.... 9. At 8:46 a.m. on Sept. 11, 2001, America was changed forever. Sept. 11 victims' loved ones will gather at ground zero to commemorate the attacks' anniversary with the reading of names, moments of silence and serene music that have become tradition 10. A man stood in the rubble and called out, asking if anyone needed help, after the collapse of the first World Trade Center Tower on Sept. 11, 2001. More than 2,700 people were killed when Al Qaeda terrorists hijacked US passenger jets and flew them into the Twin Towers in New York. Doug Kanter/AFPThick smoke billows into the sky from the area behind the Statue of Liberty where the World Trade Center towers stood. (Daniel Hulshizer/AP)