UPDATE: 9/16/13 9:30 PM CDT
WASHINGTON (AP) -- D.C. Police Chief Cathy Lanier says authorities believe there was only a lone gunman responsible for the Navy Yard shooting rampage that left 13 people dead.
Authorities had earlier said they were searching for a possible second suspect.
Mayor Vincent Gray says the 12 shooting victims range in age from 46 to 73 years old. The gunman, identified as 34-year-old Aaron Alexis, was also killed.
Gray said at a news conference late Monday night that they are still notifying the families of about half of the 12 people who were killed.
The FBI says the gunman used a valid pass to get on to the Navy Yard.
UPDATE: 9/16/13 5:36 PM CDT
WASHINGTON (AP) -- Defense officials say the suspected Washington Navy Yard gunman was currently working as a defense department contractor, but it's not clear if he was assigned at the military base in southeast D.C.
Defense officials say Aaron Alexis, 34, of Texas, was working as an information technology contractor, but it was not known which company employed him. As a contractor, he could have had a badge that might have gained him access to the base. Alexis was a former Navy reservist, serving from 2007 to early 2011.
The two officials spoke on condition of anonymity because they were not authorized to discuss it publicly.
Embry-Riddle Aeronautical University also says he was an online student pursuing a bachelor's degree in aeronautics. He started classes in July 2012.
Thirteen people were killed during the shooting rampage at Building 197. More than a dozen others were wounded.
UPDATE: 9/16/13 3:23 PM CDT
WASHINGTON (AP) -- The D.C. mayor says 13 people have died in the shooting rampage, including the gunman.
Mayor Vincent Gray said at a news conference Monday afternoon that the shooter was among the dead. Officials say the gunman has been identified as 34-year-old Aaron Alexis.
Earlier in the day, authorities had been looking for two other people who may have been involved in the shooting. One of those people has been identified and ruled out as a suspect.
However, Gray says investigators are still searching for a third individual wearing an olive-green, military-style uniform to determine if he was involved.
Gray says a motive has not yet been determined.
UPDATE: 9/16/13 2:33 PM CDT
WASHINGTON (AP) — Senate officials say no one is being allowed in or out of Senate buildings while authorities search for a potential second suspect in the Navy Yard shootings.
Senate Sergeant at Arms Terrance Gainer said Monday that people could move around the buildings but could not leave or enter. He said he had no information to suggest the Senate, its members or staff were in danger but took the step out of an abundance of caution.
The House remained open.
Authorities said as many as two gunmen opened fire Monday morning inside the Washington Navy Yard, killing at least 12 people in an attack on office workers at the heavily secured military installation in the nation's capital. One gunman was dead and police hunted for a second possible attacker.
Police say a man in a tan, military-style outfit who had been sought in connection with the shooting rampage at the Washington Navy Yard has been identified and is not a suspect or a person of interest in the slayings.
The D.C. Police Department said in a tweet Monday that the man has been identified and is not believed to be a gunman or otherwise involved in the shootings that left 12 dead.
One gunman is dead.
Chief Cathy Lanier had said earlier in the day that police were searching for two other people wearing military-style uniforms. It wasn't known if those two people were actually military employees.
UPDATE: 9/16/13 11:52 AM CDT
WASHINGTON (AP) — President Barack Obama is mourning what he called "yet another mass shooting" in the United States that he says took the life of American patriots.
Obama promised to make sure, quote, "whoever carried out this cowardly act is held responsible."
He said several people were shot Monday morning at the Washington Navy Yard about 3 1/2 miles from the White House, and some were killed.
He said the victims were "courageous Americans" who knew about the risks of serving overseas, but wouldn't have expected such "unimaginable violence" at home.
The White House says the president has been receiving frequent briefings about the unfolding situation by senior aides.
UPDATE: 9/16/13 11:13 AM CDT
WASHINGTON (AP) — Two Navy officials say at least six people have died in a shooting at the Washington Navy Yard.
The officials spoke on condition of anonymity on Monday because they were not authorized to discuss the situation publicly.
A Defense Department official and a federal law enforcement official have said a shooter had died, though it was not immediately clear how.
Police are also looking into the possibility of a second shooter.
UPDATE: 9/16/13 10:52 AM CDT
WASHINGTON (AP) — 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.
A federal law enforcement official and a Defense Department official said Monday morning that a shooter had died. Both spoke on condition of anonymity because they were not authorized to discuss the ongoing investigation.
Two other officials have said they are looking into the possibility of a second shooter at the Navy Yard.
WASHINGTON (AP) — A Defense Department official says several people have been killed and as many as 10 have been wounded in a shooting at the Washington Navy Yard.
The official spoke on condition of anonymity because the official was not authorized to discuss the matter publicly.
The official also says the shooter is "contained" but not yet in custody.
WASHINGTON (AP) — The U.S. Navy says one person is injured after a shooting at a Navy building in Washington.
Police and emergency crews gathered Monday morning outside the Naval Sea Systems Command Headquarters building, where the shooting was reported.
The Navy says three shots were fired and that that about 3,000 people work in the building. People inside the building have been directed to stay in place.
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.
Police from multiple local and federal agencies were responding along with SWAT crews.
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