A U.S. Airman with the honor guard at Bagram Airfield, Afghanistan, holds an American flag at the conclusion of a retreat ceremony officiated by Brig. Gen. Mark D. Kelly, the commander of the 455th Air Expeditionary Wing, at the airfield's Camp Cunningham Sept. 11, 2014, during an event to mark the anniversary of 9/11. More than 200 Airmen attended the event. Terrorists hijacked four passenger aircraft Sept. 11, 2001. Two of the aircraft were deliberately crashed into the World Trade Center in New York; one was crashed into the Pentagon; the fourth crashed near Shanksville, Pa. Nearly 3,000 people died in the attacks.