About 8:15 local time (12:15 GMT), Alexis entered Building 197, headquarters for Naval Sea Systems Command, which builds and maintains ships and submarines for the Navy, and opened fire.
Armed with a shotgun and a pistol he took from a guard he had shot, he sprayed bullets down a hallway and fired from a balcony down on to workers in an atrium.
He fired on police officers who eventually stormed the building, and was later killed in the shootout.
Multiple sources in the Capitol Police department have told the BBC that its highly trained and heavily armed four-man Containment and Emergency Response Team (Cert) was near the Navy Yard when the initial report of an active shooter came in about 8:20 local time.
The officers, wearing full tactical gear and armed with HK-416 assault weapons, arrived outside Building 197 a few minutes later, an official with knowledge of the incident told the BBC.
... According to a Capitol Police source, an officer with the Metropolitan Police Department (MPD), Washington DC's main municipal force, told the Capitol Cert officers they were the only police on the site equipped with long guns and requested their help stopping the gunman.
When the Capitol Police team radioed their superiors, they were told by a watch commander to leave the scene, the BBC was told.
The gunman, Aaron Alexis, was reported killed after 09:00.Rollcall reports:
“Stunned” and “embarrassed” were among the reactions overheard from officers posted around the Capitol complex discussing the allegations that one of the best-trained tactical units in the city was ordered to leave the scene of a mass shooting.
In response to the revelations, the Capitol Police Board — Senate Sergeant-at-Arms Terrance Gainer, House Sergeant-at-Arms Paul Irving, Architect of the Capitol Stephen Ayers and Capitol Police Chief Kim Dine — on Wednesday established at Dine’s request a “Fact Review Team led by Michael Stenger, Assistant Sergeant at Arms for Protective Services and Continuity and former Assistant Director of the U.S. Secret Service” to get to the bottom of the questions, according to a release from the board.
“The review team will conduct its work and report its findings and recommendations to the Capitol Police Board and Chief Dine no later than October 21, 2013,” the release said.I predict that the media will brush this under the carpet very quickly.