AP Photo/ Evan Vucci
A U.S. Park Police helicopter continues a search pattern above the scene of a shooting at the Washington Navy Yard on Monday, Sept. 16, 2013 in Washington. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning, and officials said several people were killed and more were wounded, including a law enforcement officer.
AP Photo/Manuel Balce Ceneta
Police who responded to shooting at the Washington Navy Yard Monday, Sept. 16, 2013, leave the facility. At least one gunman launched an attack inside the Washington Navy Yard, spraying gunfire on office workers in the cafeteria and in the hallways at the heavily secured military installation in the heart of the nation's capital, authorities said.
AP Photo/Jacquelyn Martin
People hold their hands to their heads as they are escorted out of the building where a deadly shooting rampage occurred at the Washington Navy Yard in Washington, Monday, Sept. 16, 2013. One shooter was killed.
Associated Press/Don Andres
People tending to a person lying on a sidewalk near the area where a gunman was reported at the Washington Navy Yard in Washington, on Monday, Sept. 16, 2013.
Don Andres/Associated Press
People tending to a person lying on a sidewalk near the area where a gunman was reported at the Washington Navy Yard in Washington, on Monday, Sept. 16, 2013.
AP Photo/Susan Walsh
A U.S. Park Police helicopter with a person in the rescue basket, flies over a building at the Washington Navy Yard in Washington, Monday, Sept. 16, 2013. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning.
Jacquelyn Martin/AP
Emergency vehicles and law enforcement personnel respond to a reported shooting at the Washington Navy Yard September 16, 2013 in Washington, DC.
Alex Wong/Getty Images
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.
Alex Wong/Getty Images
Two DC Metro Police officers respond to a reported shooting at an entrance to the Washington Navy Yard September 16, 2013 in Washington, DC.
Saul Loeb/AFP/Getty Images
Police and firefighters respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013.
Saul Loeb/AFP/Getty Images
Police respond to the report of a shooting at the Navy Yard in Washington, DC, September 16, 2013.