The US Capitol is in lockdown, following shots fired outside the US Capitol Building on Thursday afternoon.

The Washington Post reports that Capitol police were telling people to take shelter in place, amid the lockdown. The incident appeared to begin around 2:19 p.m. and Capitol police say the Capitol was locked down.

USA Today tweeted: "In a notice distributed by email, the U.S. Capitol Police advised everyone to "close, lock and stay away from external doors and windows.""

USA Today also tweeted: "CNN quotes Senate Majority Leader Harry Reid as saying there has been "one injury.""

There are no further details regarding the injury.

Officers with semi-automatic weapons were seen running for the exits on the first floor of the House side of the Capitol, The Washington Post reports.

Sen. Charles Schumer has confirmed there have been shots fired outside the U.S. capitol.

Differing reports claim 8 - 12 shots were fired.

No one would say whether any shots were fired inside the capitol.

Senate Sergeant at Arms Terrance W. Gainer told reporters there were reports of injuries.

The Washington Post said a reporter claimed a shooter has been arrested.

Floor activity in the House of Representatives has been temporarily halted.