Sept. 11 Memorial Ruck March
Senior Airman Samuel O'Brien with the 377th Special Forces Group carries the U.S. Flag during a ruck march commemorating the victims of the 9-11 attacks here. The march started at 6:46 a.m. (8:46 EDT, to mark the start time of when the first plane hit the twin towers 17 years ago. (U.S. Air Force photo by Jessie Perkins)