White House security alert as roads closed in Washington DC amid reports of an "active shooter"

An area close to the White House has been cordoned off in the course of reports of a gunman on the loose.

Police said a number of blocks near a busy intersection in downtown Washington DC had been closed early this morning.

Busy: The K Street corridor in Washington DC houses law firms and lobbyists

An update at 3.50 am said an armed suspect had been contained within an office building and that no injuries were reported, according to the Washington Post.

Warning: Officials from the George Washington University issued an advisory

It followed an advisory from George Washington University (GWU) to its campus community at around 3am, warning of an "active shooter" near 19th and K Streets.

However, while police said a person suffering a mental health crisis had been barricaded in the area, they could not confirm that any shots had been fired.

Officials from GWU urged students to avoid the area.

Scene: The "active shooter" was reported in an area close to the White House

It added that police and Secret Service officers were on the scene.

Police provided details of road closures on Twitter.

They also confirmed there had not been an "active shooter situation".

ROAD CLOSURES, police activity: 18th to 21st Streets on M through K and K through M on 18th,19th 20th and 21st Streets. Please avoid area

— DC Police Department (@DCPoliceDept) November 16, 2015

Barricade: 19th&K Streets(UPDATE)-No injuries reported, was not an active shooter situation. Subject contained, investigation continuing.

— DC Police Department (@DCPoliceDept) November 16, 2015

The area is just a few blocks away from Pennsylvania Avenue and the White House, historic home and office of the US president Barack Obama.

Elsewhere in the city, a stabbing was reported in the 1200 block of Connecticut Avenue shortly after 3am.

The site located three or four blocks from the scene of the alleged shooter.

It is not clear if the incidents were connected.

The K Street corridor is lined with office buildings housing law firms and lobbyists.