USA: Capitol Hill Lockdown with reports of gunfire -lockdown now lifted, but security forces remain at scene

Capital Hill in the United States was in lockdown after reports of shots being fired at the site, but the lockdown has now been lifted.  There are reports that the incident began outside the home of the US President The White House before moving to Capitol Hill. A police cordon was immediately put in place at the scene. A announcement was broadcast saying: "This is an emergency". Hundreds of police vehicles attended the scene in Washington, along with ambulance emergency response vehicles. There are reports of injuries following the incident with at least four short reported to have been heard. The lockdown has now been lifted, meaning congressional staff are allowed to freely leave any area they were sheltering in, following the incident - however the security operation remained in place for some time after.
Image from @KatyNocera