Police say Washington Navy Yard shooter acted alone

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Washington, DC Police say a gunman that killed 12 people and injured sixteen others at the Washington Navy Yard before being killed acted alone in the shooting.

Police Chief Cathy Lanier spoke at a news conference Monday afternoon and confirmed the deaths of 12 victims and the shooter, 34-year-old Aaron Alexis, a civilian contractor from Fort Worth, Texas.

It is believed Alexis stole an employee ID to gain entry into the building. It is not clear how he died during the incident.

The Washington DC police chief said Monday night they believe Alexis acted alone in the shooting. Earlier in the day, police said two additional shooters could be at large.

Alexis seems a study in contradictions: a former Navy reservist, a Defense Department contractor, a convert to Buddhism who was taking an online course in aeronautics. But he also had flashes of temper that led to run-ins with police over shootings in Fort Worth and Seattle.

While some neighbors and acquaintances described him as "nice," his father once told detectives in Seattle his son had anger management problems related to post-traumatic stress brought on by the terrorist attacks of Sept. 11, 2001.

He also complained about the Navy and being a victim of discrimination.

Washington DC Mayor Vincent Gray says the victims ranged in age from 46 to 73 years old. Among those wounded are two law enforcement officers.

The shooting took place around 8:20 am. At around 11:40 am, the Associated Press reported that the shooter was dead. NBC News confirmed that report.

A spokesperson for the Medstar Hospital in Washington said they were treating three gunshot victims, including a male DC police officer and two women. All three were in critical condition but were able to speak to medics. One had gunshot wounds to the legs; another was shot in the head and hand and another was shot in the shoulder.

While their injuries are severe, the hospital spokesperson said they all have strong chances of survival.

The hospital spokesperson said more victims are expected.

Reagan International Airport was placed on a ground stop during the incident, but as of 11:00 am flights were operating again.

Police and emergency crews gathered Monday morning outside the Naval Sea Systems Command Headquarters building, where the shooting was reported.

The Navy says several shots were fired and 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.

Seven DC-area schools were on lockdown.

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