Sounds similar to gunfire have been heard close to the Palace of Westminster.

A man with a knife charged through the gates into the front yard of the Palace, eyewitnesses said.

Two people were seen lying within Old Palace Yard, immediately outside Westminster Hall.

Minutes after the incident, an emergency services helicopter landed in Parliament Square, as sirens were heard outside.

Air ambulance medics came from the helicopter to assist the casualties.

The sitting in the House of Commons has been suspended while police officers sealed off the area around the incident.

Scotland Yard said it was called to a firearms incident on Westminster Bridge amid reports of several people injured.

The Deputy Leader of the Democratic Unionist Party said: "Commons lock down. MPs in chamber."