Gunman opens fire at Navy Yard in Washington, D.C.,2.6miles from the White house.... 15 dead

• FBI identifies shooting suspect
• contractor responsible for the death of over 15 people
• Several wounded after gunman opens fire at Washington Navy Yard
• Shots fired in Washington Navy Yard, multiple injuries

By Phil Stewart, Ian Simpson and Deborah Charles

WASHINGTON | Tue Sep 17, 2013 4:44am EDT

(Reuters) - A U.S. military veteran opened fire at the Washington Navy Yard on Monday in a burst of violence that killed 13 people, including the gunman, and set off waves of panic at the military installation just miles from the White House and U.S. Capitol.
The FBI identified the suspect as Aaron Alexis, 34, of Fort Worth, Texas, a Navy contractor who had two gun-related brushes with the law. He was discharged from the Navy Reserve in 2011 after a series of misconduct issues, a Navy official said.
He was killed in one of several gun battles with police after he entered the Naval Sea Systems Command headquarters about 8:20 a.m. (1220 GMT) and started picking off victims in a cafeteria from a fourth-floor atrium, witnesses said.
That set off pandemonium, with fire alarms sounding and security officers yelling at people to leave the building. Hundreds fled, some scrambling over walls to escape the gunfire. A loudspeaker announcement ordered those who remained to stay in their offices.
The motive remained unknown. He was armed with an AR-15 military-style assault rifle, a double-barreled shotgun and a handgun, a federal law enforcement source said.
Eight people were injured including three who were shot, Washington Mayor Vincent Gray said. Those killed were aged 46 to 73, he said. Investigations continued into the circumstances of their deaths.
Investigators earlier were pursuing a possible second gunman but later said there were no suspects beyond Alexis. The incident has raised questions about security at the Washington Navy Yard, about a mile south of the U.S. Capitol and 3 miles from the White House.
Alexis, a contract employee, had legitimate access to the Navy Yard and used a valid pass, the FBI said. Authorities did not address how he could have sneaked weapons onto the base.
Police patrol officers and active shooter teams put an end to the rampage, shooting Alexis dead. Washington Metropolitan Police Chief Cathy Lanier said the gun battles produced acts of heroism she could not yet reveal.
"Everybody was panicking and trying to decide which way to get out. A few of us just ran out the side exit," Patricia Ward, who works at the Navy Yard, told reporters.
Security guards told people to "run, run, run," Ward said.
It was the worst attack at a U.S. military installation since U.S. Army Major Nidal Hasan opened fire on unarmed soldiers at Fort Hood, Texas, in 2009, killing 13 people and wounding 31 others. Hasan, who said he acted in retaliation for U.S. wars in Muslim countries, was convicted and sentenced to death by a military jury in August.
"We are confronting yet another mass shooting, and today it happened at another military installation, in our nation's capital," said U.S. President Barack Obama, who vowed to enact "sensible" gun control measures after a gunman shot dead 20 school children and six adults at an elementary school in Connecticut in December.