WESTMINSTER has been evacuated and Parliament is on lockdown after a man stormed the palace and stabbed a police officer.
A number of pedestrians were also injured when a vehicle ploughed into the crowd while crossing northbound over Westminster Bridge.
It's not known whether the driver of the vehicle and the armed man are related.
A man, who is described as middle aged, attempted to gain entry to the Palace Court at the side of the palace armed with a knife shortly before 2.45pm this afternoon.
After stabbing a police officer, he was then shot by other police officers.
It's understood a Northern Irish MP attempted to give first aid to the injured police officer before help arrived.
Sources at the scene told The Irish Post that offices facing the street in Portcullis House have been evacuated and the staff are being held in the central lobby.
Parliament has been suspended but MPs are being held on lockdown in the Chamber.
It's understood they were voting at the time of the incident.
Paraic O'Brien, a reporter with Channel 4, spoke to a doctor on Westminster Bridge who witnessed the incident.
One of the first doctors on Westminster Bridge describes one confirmed dead, 12+ injuries, including this one: pic.twitter.com/NDC8cH2YrO
— Paraic O'Brien (@paraicobrien) March 22, 2017
Police are asking people to avoid the following areas: Parliament Square; Whitehall; Westminster Bridge; Lambeth Bridge; Victoria Street up to the junction with Broadway and the Victoria Embankment up to Embankment tube.
This is to allow the emergency services to deal with the ongoing incident.
Met Police have said, "Officers - including firearms officers - remain on the scene and we are treating this as a terrorist incident until we know otherwise."
An Air Ambulance has also been despatched.
The London Eye is also on lockdown, and police are searching Westminster Palace room by room.