U.S. Airmen with the Davis-Monthan Air Force Base First Sergeants Council and the 43rd Electronic Combat Squadron participate in the Never Forgotten 9/11 Tower Challenge at the University of Arizona Football Stadium in Tucson, Ariz., Sept. 11, 2014. The Greater Tucson Fire Foundation hosted the event to honor those who lost their lives in the 9/11 terrorist attacks. 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 (U.S. Air Force photo by Airman 1st Class Chris Massey/Released)