A gunman shot dead 12 people and wounded about a dozen others before being killed by police Monday at a U.S. Naval facility in Washington, DC.
Police identify the gunman as a former military contractor . They say it is not clear how he got access to the U.S. Navy Yard without proper identification or what his motive was. Washington Mayor Vincent Gray says there is no reason to believe this was a terrorist attack.
Police say they are still seeking a second person seen in a surveillance video who may have been involved.
At the White House, President Barack Obama said he is mourning "yet another mass shooting.'' He called it a "cowardly act'' and said the victims and their families need America's love and support.
He has ordered flags across the country to fly at half-staff through sunset Friday to honor the victims.
Police say the 34-year-old man opened fire at Washington's Navy Yard's Naval Sea Systems Command building. About 3,000 people, mostly civilians, work there. The Command is in charge of buying, building and maintaining ships and submarines.
The Navy Yard is in a residential area close to the U.S. Capitol. People in the neighborhood were ordered to stay in their homes and offices. A number of schools and U.S. Senate offices were locked down.
Monday night's baseball game between the Atlanta Braves and the host Washington Nationals at a nearby stadium also was canceled.