-- Investigators now do not think there was a second shooter, D.C. Police Chief Cathy Lanier said late Monday evening. Throughout Monday, authorities had run down witness reports and other evidence indicating there might have been additional gunmen.
Aaron Alexis, whom the FBI believes to have been responsible for the shootings at the Washington Navy Yard in Washington, D.C., is shown in this handout photo released by the FBI on Monday.
Credit FBI / Reuters/Landov
Aaron Alexis, the 34-year-old man believed responsible for Monday's shooting rampage that killed 12 people at the Washington Navy Yard, was a former full-time Navy reservist who had obtained a concealed-carry permit in Texas and was arrested three years ago for illegally discharging a weapon.
King George VI and Queen Elizabeth arrive at the Washington Navy Yard on June 9, 1939, to join President Franklin Roosevelt on a cruise down the Potomac River to Mount Vernon, Va.
The sprawling Washington Navy Yard, scene of a deadly shooting Monday, is the Navy's oldest shore establishment and has long been considered the "ceremonial gateway" to the nation's capital.
The yard went into operation at the turn of the 19th century. Today, it employs thousands of people and is regarded as the "quarterdeck of the Navy" for its role as headquarters for the Naval District Washington.
Workers emerge from a building after a deadly shooting at the Washington Navy Yard on Monday. There are multiple injuries and deaths, and one gunman is dead. Police say they are searching for two other "potential" shooters.