There are reportedly multiple fatalities in Washington, DC Monday morning after no fewer than two gunmen opened fire at Navy Yard, injuring at least 10 and killing four, according to preliminary reports.

649 GMT: Authorities believe that one shooter is dead and as many as two other suspects are on the loose. Sources speaking to ABC this afternoon said that one of the shooters may be a former Navy official. Meanwhile, the DC Metropolitan Police Department report that at least one of the shooters appeared to be in official military clothing.

1634 GMT: At a press conference Monday afternoon, President Barack Obama said of the Navy Yard shooting, “We will do everything in our power to make sure whoever carried out this cowardly act is held responsible.”

1634 GMT: At a press conference Monday afternoon, President Barack Obama said of the Navy Yard shooting, “We will do everything in our power to make sure whoever carried out this cowardly act is held responsible.”

1627 GMT: Department of Defense officials tell CNN that they have increased security at the Pentagon following a shooting Monday morning 5 miles away at DC’s Navy Yard.

1613 GMT: DC Mayor Vincent Gray said at a press conference just after 12 noon local time that officials “are still trying to confirm the number of fatalities involved.” 

Cathy Lanier, the DC chief of police, added, “I will not give a confirmed number at this time, but I would say we have multiple victims inside who are deceased.”

Lanier also said that one suspected shooter is dead and that authorities believe that there are “potentially” two other shooters who have not yet been located.

1606 GMT: Navy officials tell the Associated Press that there are now six confirmed fatalities following Monday’s rampage at Navy Yard, DC.

1538 GMT: Three of the Navy Yard shooting victims are in critical condition but have “very good” chance of surviving, Janis Orlowski, chief medical officer at Washington Hospital Center, tells reporters.

The three victims at WHC, Orlowski says, include one male and two females. One has injuries to the legs, another was shot in the shoulder and a third has gunshot wounds to the head and hand. 

“They do have severe injuries but we have been able to speak to all of them,” she said. 

There are currently three victims at WHS, but Orlowski says the hospital is expecting more. 

1534 GMT: RT’s Sam Sacks reports from Navy Yard that there is “a flurry of activity” as several police cars race around southeast DC near Navy Yard.

1526 GMT: One of the suspected shooters is dead, two different law enforcement sources have confirmed to DC’s NBC affiliate.

1519 GMT: Law enforcement sources tell CNN that the same Bureau of Alcohol, Tobacco, Firearms and Explosives team that assisted with the Boston Marathon bombing have been deployed to Navy Yard.

A US Park Police helicopter patrols over the US Navy Yard September 16, 2013 in Washington,DC.(AFP Photo / Paul J. Richards)

1513 GMT: Federal Bureau of Investigation sources tell Fox News that an FBI SWAT team is working with other agencies to clear out the building at Navy Yard where at least one shooter is thought to be hiding.

A general view shows police and first responder activity on M Street, SE near the Washington Navy Yard on September 16, 2013 in Washington, DC.(AFP Photo / Mandel Ngan)

1506 GMT: A representative for the Naval District of Washington Public Affairs office tells reporters that two shooters are “down.” A press conference is scheduled to begin shortly.

1451 GMT: Washington Post is now reporting that two shooters may have been responsible for the Monday morning rampage. Initially the paper reported a lone gunman, then three, opened fire at DC’s Navy Yard.

A helicopter pulls what appears to be a shooting victim up as it hovers over a rooftop on the Washington Navy Yard campus in Washington, September 16, 2013.(Reuters / Jason Reed)

1444 GMT: Of the 10 people reportedly shot, police say eight are civilians, one is a DC police officer and another is a Navy Yard base officer.

Members of various law enforcement agencies are pictured at the Washington Navy Yard campus in Washington, September 16, 2013. (Reuters / Jason Reed)

1442 GMT: Two hours after gunshots were first reported, police tell local networks that at least one active shooter is still at large.

1437 GMT: At least six DC-area schools near Navy Yard have been placed on lockdown as a precaution following Monday morning’s shooting.

1430 GMT: Police sources have told the Washington Post that there are at least three shooters are thought to be responsible for the Navy Yard incident.

Members of the United States Marine Corps maintain a watch on their barracks as police respond to a shooting at the Washington Navy Yard, in Washington September 16, 2013.(Reuters / Joshua Roberts)

1428 GMT: Reagan National Airport in Northern Virginia near downtown DC has been re-opened following a brief closure ordered as a result of the Navy Yard shooting. 

1421 GMT: A senior Naval officer has told NBC News that there are multiple shooters responsible for the outburst Monday morning, and that at least four victims are confirmed dead. 

1412 GMT: Navy have confirmed that there have been "some fatalities" as result of the shooting. The confirmed number of those wounded has risen to ten.

Police block off M Street, SE as they respond to a shooting at the Washington Navy Yard, in Washington September 16, 2013. (Reuters / Joshua Roberts)

1408 GMT: Police have closed M Street and 11th Street Bridge by the shipyard due to the incident. A police helicopter has landed on the bridge. 

1405 GMT: Police are acting on reports US Navy Yard shooter may have gone on roof. 

1400 GMT: 
 

UPDATE: FAA has grounded all flights at National Airport in D.C. due to Navy Yard incident -http://t.co/wGJd3irJox #navyyardshooting

— CBS News (@CBSNews) September 16, 2013

Emergency vehicles and law enforcement personnel respond to a reported shooting at an entrance to the Washington Navy Yard September 16, 2013 in Washington, DC.(AFP Photo / Alex Wong)

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