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.
Gunman in Navy Yard shooting was in Navy Reserves
Defense officials say Aaron Alexis, identified as the gunman who opened fire at the Washington Navy Yard, was a full-time Navy reservist from 2007 to 2011 and worked recently as a Defense Department contractor.
He also prayed at a Buddhist temple, was taking online course in aeronautics and was involved in past shooting incidents which attracted police attention in Seattle and Fort Worth, Texas.
It was not immediately clear why Alexis left the reserves, who his latest employer was, or what his motives might have been for going on a rampage. He was one of 13 people killed during Monday's shootings.
Police in Seattle say Alexis was arrested there in 2004 for shooting out the tires of another man's vehicle in what he described to detectives as an anger-fueled "blackout."
Obama orders flags lowered for shooting victims
WASHINGTON (AP) -- The White House says President Barack Obama is ordering flags to be lowered to half-staff to honor victims of a shooting at the Washington Navy Yard.
A proclamation Obama signed Monday says flags should be lowered immediately and will remain there until sunset on Friday. The proclamation applies to all public grounds, military posts and naval vessels, plus U.S. embassies and outposts overseas.
Authorities say a former Navy man launched an attack inside a building at the Navy Yard, spraying gunfire on office workers in the cafeteria and in the hallway at the heavily secured installation. Thirteen people were killed, including the gunman.
Navy Yard shooting shakes Fort Hood victims
HOUSTON (AP) -- Survivors and relatives of those killed in the shooting rampage at the Fort Hood military base in Texas say the attack at the Navy Yard in Washington has brought back memories from 2009.
The shooting in Washington on Monday came just weeks after Nidal Hasan was convicted and sentenced to death for killing 13 people and wounding dozens at Fort Hood.
Kathy Platoni watched a friend bleed to death in Fort Hood. She watched the Navy Yard news unfold at a doctor's office. She says she tried to hide her shaking from other patients.
Keely Cahill's father, Michael Cahill, was killed by Hasan when he tried to stop the rampage. She says she keeps thinking of families sitting and waiting for news about their loved ones.
The two officials spoke Monday to The Associated Press on condition of anonymity because they were not authorized to speak publicly.
One of those officials says Alexis was a 34-year-old from Texas. He is believed to have a criminal record there and to be a holder of a concealed carry weapon permit.
That official says Alexis is believed to have gotten into the Navy Yard by using someone else's identification card. It is not yet clear if that individual was an accomplice or if that person's ID card was stolen.
WASHINGTON (AP) -- Police say at least 12 people have died in the shootings at the Washington Navy Yard.
D.C. Police Chief Cathy Lanier said during a news conference Monday that 12 people were confirmed dead.
Lanier says people are being told to stay in their homes and out of the area as authorities search for two other possible suspects. One of the shooters has died.
The police chief says officers are searching for two other people with firearms wearing military-style uniforms.
She says there is no indication of a possible motive at this time.
WASHINGTON (AP) -- Authorities say they are looking for two additional suspects in the shooting rampage at the Washington Navy Yard.
District of Columbia Police Chief Cathy Lanier says witnesses reported seeing two additional gunmen, both dressed in military-style clothing.
Lanier says one police officer was wounded in an exchange of gunfire with a shooter. She says one shooter has been killed.
Two Navy officials say at least six people were killed in the rampage.
D.C. Mayor Vincent Gray said at a Monday news conference four people were wounded and taken to hospitals.
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.
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.
As many as 10 were wounded.
WASHINGTON (AP) -- Two officials say police are looking into the possibility of a second shooter at the Washington Navy Yard where several people were killed.
A Defense Department official and a law enforcement official spoke on condition of anonymity Monday because they were not authorized to discuss the ongoing investigation.
At least one gunman opened fire inside the Naval Sea Systems Command headquarters, where about 3,000 people work just miles from the Capitol.
Among the wounded was a D.C. police officer, according to a law enforcement official who spoke on the condition of anonymity because the person was not authorized to discuss an ongoing investigation.
At least 10 were wounded.
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 Monday because the official was not authorized to discuss the matter publicly.
The official also says the shooter is "contained" but not yet in custody.
Earlier in the day, the U.S. Navy said it was searching for an active shooter at the Naval Sea Systems Command headquarters, where about 3,000 people work.
The exact number of people killed and the conditions of those wounded was not immediately known.