WASHINGTON — A defense-industry employee used his pass to get into the Washington Navy Yard and went on a deadly shooting rampage Monday, spraying bullets in the hallway and firing from a balcony on workers in an atrium below. Thirteen people were killed, including the gunman.
The motive for the assault — the deadliest shooting on a military installation in the U.S. since the tragedy at Fort Hood, Texas, in 2009 — was a mystery, investigators said.
Mayor Vincent Gray said there was no indication it was a terrorist attack, but he added that the possibility had not been ruled out.
"This is a horrific tragedy," he said.
The onslaught at a single building at the highly secure Navy Yard unfolded about 8:20 a.m. in the heart of the nation's capital, less than four miles from the White House and two miles from the Capitol.
It put all of Washington on edge and raised the specter of another well-coordinated terrorist strike — or another attack from within, like Fort Hood.
The gunman, Aaron Alexis, a 34-year-old information technology employee and former Navy reservist whose last known address was in Fort Worth, Texas, died after a running gunbattle inside the building with police, investigators said.
He carried three weapons: an AR-15 assault rifle, a shotgun, and a handgun that he took from a police officer at the scene, according to two federal law enforcement officials who spoke on condition of anonymity because they were not authorized to discuss the investigation.
For much of the day, authorities said they were looking for a possible second attacker who may have been disguised in an olive-drab military-style uniform.
But by late Monday night, they said they were convinced the shooting was the work of a lone gunman, and the lockdown around the area was eased.