WASHINGTON -- A mass shooting Monday at the Washington Navy Yard left at least 13 people dead, including a suspected gunman, three others wounded and authorities desperately searching as night fell for a middle-age man in a military-style uniform.
It was perhaps the most devastating shooting attack in the heavily guarded nation's capital in decades and sparked new concerns about security at U.S. military facilities.
District of Columbia police Chief Cathy Lanier identified the gunman as a civilian navy contractor, Aaron Alexis, 34, of Fort Worth, Texas, who was identified by fingerprints. An employee of a Hewlett-Packard subsidiary, Alexis was a full-time navy reservist until 2011, last serving with a logistics support squadron in Fort Worth.
Two federal officials speaking on the condition of anonymity said Alexis was carrying three weapons during the rampage.
The officials said Alexis had an AR-15 assault rifle, a shotgun and a handgun that he took from a police officer at the scene.
The FBI says Alexis used a valid pass to get on the Washington base.
By nightfall, authorities were still seeking to question a black man between 40 and 50 years old, described as wearing an olive-coloured military-style uniform. It was unclear whether he was involved in the shooting or whether Alexis was a lone gunman. Lanier said a potential third suspect was cleared of any involvement.
Alexis had a police record for gun-related incidents in the states of Texas and Washington, according to legal documents and law enforcement.
Friends say Alexis regularly meditated at a local Buddhist temple, was unfailingly courteous and never showed signs of the violence that is now his legacy.
Nutpisit Suthamtewakul, owner of Happy Bowl Thai in the Fort Worth area, told the Fort Worth Star-Telegram Alexis was "my best friend."
"He lived with me three years," Suthamtewakul said Monday afternoon. "I don't think he'd do this. He has a gun, but I don't think he's that stupid. He didn't seem aggressive to me."
The FBI posted a "Seeking Information" notice about Alexis, showing his photograph and asking for help in piecing together how and why he was in the nation's capital.
"We don't have any reason at this stage to suspect terrorism," said D.C. Mayor Vincent Gray, though he said it hasn't been ruled out.
Word that Alexis had a prior rap sheet spread in late afternoon. Police records in Fort Worth show that on Sept. 4, 2010, officers were dispatched to his apartment when a neighbour alleged he shot a hole up through his ceiling.
Alexis was also arrested by Seattle police in 2004 after shooting out two tires of a car parked next door to his home. He told authorities that construction workers had "disrespected him."
He also told police that he had blacked out and didn't remember the shooting until hours later, according to a police report posted by the Seattle Times.
He was in the navy from 2007 to 2011 and was a petty officer third-class.
It was not immediately clear when or under what circumstances he was discharged. Friends said he left because he didn't like to get up early and had complained about being underpaid.
-- McClatchy Washington Bureau
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