The incident has been called a terror attack by the Met Police,
Police have warned people to avoid Parliament Square; Whitehall; Westminster Bridge; Lambeth Bridge; Victoria Street up to the junction with Broadway and the Victoria Embankment up to Embankment tube.
Westminster station, which faces parliament, has also been evacuated.
Armed officers are patrolling the streets after the incident and an announcement in parliament has just revealed a suspicious package was found in a vehicle.
The bomb squad is being drafted in to to assess the fresh threat.
— Met Contact Centre (@MetCC) March 22, 2017
Just before 3pm on Wednesday multiple people were injured after a car ploughed into people on Westminster Bridge, before continuing its path of destruction towards Parliament.
The driver is said to have made their way into the Old Palace Yard before stabbing an officer, before being shot by armed police.
One woman has been confirmed dead and more are said to have suffered “catastrophic injuries”.
The incident has been called a terror attack by the Met Police, forcing Parliament business to be suspended and go into lockdown.
The London Ambulance Service (LAS) has urged anyone who does not critically need an ambulance to refrain from dialling 999.
A statement from them said: “We are working closely with other members of the emergency services at the scene, with our priority being to ensure patients receive the medical help they need as quickly as possible.
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Armed officers are patrolling the streets after the incident
Only call us in a genuine emergency
London Ambulance Service
“We have declared a major incident and our priority is to assess patients and ensure that they are treated and taken to hospital as soon as possible.
“As we are very busy dealing with this incident, we would ask the public to only call us in a genuine emergency.”
The Met has also reminded people not to dial 999 unless an emergency.
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They tweeted: “Our lines are busy, please dial 999 for emergencies only.”
The Scottish parliament has also been suspended and security has been increased.
The Met is appealing for anyone with footage to get in touch on www.ukpoliceimageappeal.co.uk.
London Terror Attack: LIVE IMAGES Wed, March 22, 2017
One dead in Parliament shooting as 12 mown down in Westminster
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Emergency services at the scene outside the Palace of Westminster, London, after policeman has been stabbed and his apparent attacker shot by officers in a major security incident at the Houses of Parliament