Petty Officer 1st Class Peter York from Coast Guard Station Niagara, N.Y., stands guard over a "deceased" active shooter during an exercise held at Coast Guard Sector Buffalo, N.Y., Jan. 29, 2015. York was one of many Coast Guard law enforcement officers from Coast Guard stations throughout Sector Buffalo's area of responsibility who participated in the exercise. (U.S. Coast Guard photo by Petty Officer 3rd Class Lauren Laughlin)