Law enforcement officials say the defense contractor who fatally shot 12 people at the Washington Navy Yard was carrying three weapons during the rampage.
Two federal officials say Aaron Alexis had an AR-15 assault rifle, a shotgun and a handgun that he took from a police officer at the scene. The two officials spoke on the condition of anonymity because they were not authorized to discuss a pending investigation.
The 34-year-old man died after a running gunbattle inside the building with police.
The FBI says Alexis used a valid pass to get on the Washington base.
Alexis had been arrested in Seattle in 2004 for shooting out the tires of a parked car in what he described as an anger-fueled ``black out.''
Two construction workers told police that Aaron Alexis walked out of a home next door on May 6, 2004, pulled a pistol from his waistband and fired three shots into the rear tires of their parked car. Alexis later told police he thought the victims had ``disrespected him.''
Court records show he was released on the condition he not have contact with any of the construction workers.
Seattle police said in a statement Monday that detectives later spoke with Alexis' father, who told police Alexis had anger management problems associated with PTSD, and had participated in rescue attempts on Sept. 11, 2001.
The Senate is returning to normal operations Tuesday following a shutdown due to the Navy Yard shootings.
Terrence Gainer, the Senate sergeant at arms, had restricted people from leaving or entering Senate buildings for part of the day Monday as authorities were searching for other potential shooters. Late Monday, however, authorities said they believed the gunman operated alone. Thirteen people, including the gunman, died in the shooting at the Navy Yard, about a mile south of the Capitol.
Gainer said that while operations are returning to normal, the U.S. Capitol Police will maintain a high level of security at the Capitol complex.
The shooting was the deadliest on a military installation in the U.S. since the tragedy at Fort Hood in 2009.
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