Navy Yard: Swat team 'stood down' at mass shooting scene
...A tactical response team of the Capitol Police, a force that guards the US Capitol complex, was told to leave the scene by a supervisor instead of aiding municipal officers.

The Capitol Police department has launched a review into the matter.

Aaron Alexis, 34, killed 12 people at the Washington Navy Yard.

"I don't think it's a far stretch to say that some lives may have been saved if we were allowed to intervene," a Capitol Police source familiar with the incident told the BBC....

...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....

Navy Yard shooting: Swat team awaits answers
The Capitol Police tactical response team was told by a supervisor to leave the scene instead of aiding municipal officers, sources told the BBC.

Meanwhile, the department has installed a new leader of the elite unit. No reason has been given for the decision.

Gunman Aaron Alexis killed 12 people.

The BBC has also learned that four members of the highly trained team have applied for temporary leave, as they "grapple" with the aftermath of the incident.

The Capitol Police department has not yet granted the request, nor given approval for them to use their own paid time off. ...

...On Thursday, members of the tactical unit, which has several dozen members, were told that it had a new leader, a Capitol Police source said. It is not clear why the command shake-up occurred.

Four Cert team members wearing full tactical gear and armed with HK-416 assault weapons arrived on scene at Navy Yard at 08:36 (12:36 GMT) on Monday, after reports surfaced of an active gunman at the complex at 08:20.

According to sources, 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 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.

On Thursday, FBI Director James B Comey Jr told ABC News it took roughly half an hour for armed police to arrive and engage Alexis. All 12 victims were killed within that time.

Capitol Police sources suggest "lives may have been saved" if the Cert team had been allowed to intervene....