The Washington Navy Yard shooting occurred on September 16 , 2013 , when lone gunman Aaron Alexis fatally shot twelve people and injured three others in a mass shooting at the headquarters of the Naval Sea Systems Command ( NAVSEA ) inside the Washington Navy Yard in Southeast Washington , D.C. .
On September 16 , 2013 , Aaron Alexis , a lone man armed with a shotgun , killed twelve people and injured fourteen others in a mass shooting at the headquarters of the Naval Sea Systems Command ( NAVSEA ) inside the Washington Navy Yard in Southeast Washington , D.C. .