According to the latest report on http://www.nbcwashington.com, four people were killed and at least 10 were shot at the Washington, D.C. Navy Yard Monday morning by more than one gunman. At about 10:20 a.m., one shooter had been reported contained. However, at least one other gunman remained at large. The conditions of the victims are unknown, but George Washington Hospital reported that at least one victim has been transported to that hospital. The U.S. Navy said the shooting began at about 8:20 a.m. with three shots fired inside Building #197 at the Naval Sea Systems Command Headquarters, 1336 Isaac Hull Ave. in the Southeast section of the District. U.S. military officials say the gunman - armed with an AR-15, a military-style assault weapon - first shot the a base security officer.