US Capitol Complex in lockdown after reports of gunshots

The US Capitol Complex in Washington D.C. has been sent into lockdown after shots were heard at the US Capitol Visitor Center, US media reports.

The complex was locked down "due to a potential security threat", according to a notice sent to Capitol Hill employees.

The shooter is reportedly now in custody.

There are reports the White House and Congress has also been sent into lockdown following the shots.

This is a breaking news article. More information will be added as it comes to hand.