WASHINGTON, DC – SEPTEMBER 22: Family members mourn their loss as they attend a memorial for victims of the Washington Navy Yard shooting at the Marine Barracks September 22, 2013 in Washington, DC. President Barack Obama (3rd R) and first lady Michelle Obama (2nd R) visited with families of the victims in the deadly shooting at the Washington Navy Yard. Thirteen people, including the gunman Aaron Alexis, were killed in the incident. (Photo by Alex Wong/Getty Images)