U.S. Airmen with the 48th Civil Engineer Squadron Explosive Ordnance Disposal flight participate in a ruck march during a 9/11 memorial 5-kilometer run/walk at Royal Air Force Lakenheath, England, Sept. 11, 2014. 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.