Officials say at least one shooter has died at the Washington Navy Yard, where several people were killed and as many as 10 were wounded. The shooter who died after rampage identified as Aaron Alexis.
Police say 13 people died including the gunman. District of Columbia Police Chief Cathy Lanier says a police officer was wounded in an exchange of gunfire with a shooter.
A law enforecement official says a shooter at Washington Navy Yard has died. Police are looking into possibility of second shooter.
Lanier says witnesses reported seeing two additional gunmen, both dressed in military-style clothing. Lanier says people are being told to stay in their homes and out of the area as authorities search for two other possible suspects. One of the men was later identified and is not a suspect or a person of interest in the slayings.
She says there is no indication of a possible motive at this time.
The U.S. Navy says shots were fired around 8:20 a.m. Monday morning at the Naval Sea Systems Command headquarters, where about 3,000 people work.
The exact number of people killed and the conditions of those wounded was not immediately known.
Rick Mason, a program management analyst who is a civilian with the U.S. Navy, said a gunman was shooting from a fourth floor overlook in the hallway outside his office. He said the gunman was aiming down at people in the building's cafeteria on the first floor. Mason said he could hear the shots but could not see a gunman.
President Barack Obama is getting frequent briefings on a deadly shooting at the Washington Navy Yard. The White House says the president had several briefings about the unfolding situation by senior aides. Speaking at a news conference early Monday afternoon, Obama said, "We will hold those responsible for this `cowardly act' responsible."
The White House says Obama directed his team to stay in touch with the Navy, FBI and local officials.
"I'm deeply shocked and saddened by the shooting this morning at the Navy Yard," said Secretary of the Navy Ray Mabus in a statement . "Our thoughts and prayers are with the victims and their families. I have complete confidence in our first responders, and I continue to be completely focused on this very difficult situation."
Naval Sea Systems Command is the largest of the Navy's five system commands and accounts for a quarter of the Navy's entire budget. It builds, buys and maintains the Navy's ships and submarines and their combat systems.
The Navy says family members looking for information about their loved ones can contact the Warfighter and Family Support Center at 202-433-6151 or 202-433-9713.
Read a statement from the Navy .September 16, 2013 September 16, 2013
(Information from the Associated Press was used in this report.)