Three gunmen today went on the rampage in the high-security Washington Navy Yard located a short distance from the White House, killing seven persons and injuring several more in an audacious mass shooting.
One of the gunmen was shot dead and police said they were looking for two others who were believed to be at large.
Police said that seven persons were killed and several injured by the gunmen clad in military-style uniforms.
Washington Police chief Cathy Lanier told a news conference that one of the shooters was dead and authorities were searching for a white man and a black man.
"The big concern for us right now is that we have potentially two other shooters that we have not located at this point," Lanier said.
"We have no information to believe that either of these folks are military personnel, but we do have information that those individuals are wearing military-style uniforms," she said.
ABC News reported a gunman, identified as a 50-year-old Navy employee whose employment status had "recently changed", had died at the scene.
Speaking at the White House, President Barack Obama called for a seamless investigation by federal and local authorities and promised to bring those responsible for the attack to justice.
Hundreds of police and naval personnel surrounded the Naval Sea Systems Command headquarters, where about 3,000 service members, civilians and contractors work. The yard is located less than five kilometres from the White House.
Security at the Capitol was enhanced and several nearby schools and offices were locked down.
The shooting reportedly began at about 8:20 am when several shots were heard from inside the yard which maintains warships and submarines for the navy.
