'Silent killer' who brought death to the naval base
The gunman said nothing as he faced Terrie Durham in the hallway outside her office in the Washington Navy Yard's Building 197.
Still thinking that the office complex was being evacuated because of a fire, the executive assistant watched as the tall man in the blue fatigues levelled the rifle in his hands.
"It wasn't until he fired that I realised he was shooting at us, that he was trying to kill us," Mrs Durham said.
The shot announced yet another mass shooting in America, this time in one of the US Navy's largest facilities which is situated less than three miles from the White House, where US President Barack Obama was just preparing to receive his morning briefing from senior officials.
As Homeland Security officials gave Mr Obama the first of several updates, units from the local police, FBI and tactical "active shooter" SWAT teams were scrambled to the scene.
The labyrinthine complex, containing hundreds of rooms and miles of corridors, presented police and tactical teams with a huge challenge as they tracked reports of up to three gunmen.
Moving separately, according to witness, gunmen worked their way through the hallways firing apparently at random as uniformed personnel and civilians ran for their lives.
One of the gunmen was confirmed "down" by police shortly before midday, but in a sign of how fluid the situation remained, "potentially" two more were feared still at large.
By midday the preliminary death toll had risen to seven dead and five injured.
Then two hours later it had risen again – this time to 12.
Several hours after the shooting, Mrs Durham and other staff from the third floor office of the Navy Sea Systems Command's Team ship waited in a nearby building to be interviewed by the FBI.
They watched in silence as the television news replayed footage of the building they had just fled, now surrounded by heavily armed police.
Mrs Durham described the gunman she faced in the hallway as "dark-skinned".
"He said nothing and he looked like he was in blue fatigues like the Navy personnel wear," the 56-year-old said.
Within minutes of confirmation that a shooting was under way, all flights were grounded from the nearby Reagan National Airport and some 12 local schools were in lockdown.
Almost immediately questions were being raised over how up to three armed men, who were apparently not military personnel, had managed to penetrate a US Naval installation which workers said had "airport-style" levels of security. (© Daily Telegraph, London)