An Air Ambulance on the scene after sounds similar to gunfire have been heard close to the Houses of Parliament, London, Wednesday, March 22, 2017. The UK House of Commons sitting has been suspended as witnesses report sounds like gunfire outside. (Victoria Jones/PA via AP)
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Roads are closed off by police after sounds similar to gunfire have been heard close to the Houses of Parliament, London, Wednesday, March 22, 2017. The UK House of Commons sitting has been suspended as witnesses report sounds like gunfire outside. (Victoria Jones/PA via AP)
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An armed police officer stands on Parliament Square outside of the Houses of Parliament in London, Wednesday, March 23, 2017 after the House of Commons sitting was suspended as witnesses reported sounds like gunfire outside.(AP Photo/Kirsty Wigglesworth)
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Police on the scene after sounds similar to gunfire have been heard close to the Houses of Parliament, London, Wednesday, March 22, 2017. The UK House of Commons sitting has been suspended as witnesses report sounds like gunfire outside. (Victoria Jones/PA via AP)
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An Air Ambulance on the scene after sounds similar to gunfire have been heard close to the Houses of Parliament, London, Wednesday, March 22, 2017. The UK House of Commons sitting has been suspended as witnesses report sounds like gunfire outside. (Victoria Jones/PA via AP)
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Police close the area near Houses of Parliament, London, after sounds similar to gunfire have been heard close to the Houses of Parliament, London, Wednesday, March 22, 2017. The leader of Britain's House of Commons says a man has been shot by police at Parliament. David Liddington also said there were "reports of further violent incidents in the vicinity."London's police said officers had been called to a firearms incident on Westminster Bridge, near the parliament. Britain's MI5 says it is too early to say if the incident is terror-related. (Victoria Jones/PA via AP)
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Police secure the area on the south side of Westminster Bridge close to the Houses of Parliament in London, Wednesday, March 22, 2017. The leader of Britain's House of Commons says a man has been shot by police at Parliament. David Liddington also said there were "reports of further violent incidents in the vicinity." London's police said officers had been called to a firearms incident on Westminster Bridge, near the parliament. Britain's MI5 says it is too early to say if the incident is terror-related. (AP Photo/Matt Dunham)
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Police secure the area on the south side of Westminster Bridge close to the Houses of Parliament in London, Wednesday, March 22, 2017. The leader of Britain's House of Commons says a man has been shot by police at Parliament. David Liddington also said there were "reports of further violent incidents in the vicinity." London's police said officers had been called to a firearms incident on Westminster Bridge, near the parliament. Britain's MI5 says it is too early to say if the incident is terror-related. (AP Photo/Matt Dunham)
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MP's in House of Commons, London after a major security alert at the Palace of Westminster in London Wednesday March 22, 2017. The leader of Britain's House of Commons says a man has been shot by police at Parliament. David Liddington also said there were "reports of further violent incidents in the vicinity."London's police said officers had been called to a firearms incident on Westminster Bridge, near the parliament. Britain's MI5 says it is too early to say if the incident is terror-related. (PA via AP)
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Armed police officers enter the Houses of Parliament in London, Wednesday, March 23, 2017 after the House of Commons sitting was suspended as witnesses reported sounds like gunfire outside.(AP Photo/Kirsty Wigglesworth)
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Police secure the area close to the Houses of Parliament in London, Wednesday, March 22, 2017. The leader of Britain's House of Commons says a man has been shot by police at Parliament. David Liddington also said there were "reports of further violent incidents in the vicinity." London's police said officers had been called to a firearms incident on Westminster Bridge, near the parliament. Britain's MI5 says it is too early to say if the incident is terror-related. (AP Photo/Matt Dunham)
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epa05863549 Armed police push people back following major incidents outside the Houses of Parliament in central London, Britain 22 March 2017. Scotland Yard said on 22 March 21017 the police were called to a firearms incident in the Westminister palace grounds and on Westminster Bridge amid reports of several people injured in central London. EPA/ANDY RAIN
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Armed police officers stand guard outside the Houses of Parliament in London, Wednesday, March 23, 2017 after the House of Commons sitting was suspended as witnesses reported sounds like gunfire outside. The leader of Britain's House of Commons says a man has been shot by police at Parliament. David Liddington also said there were "reports of further violent incidents in the vicinity." (AP Photo/Kirsty Wigglesworth)
©AP 2017
Emergency services staff provide medical attention close to the Houses of Parliament in London, Wednesday, March 22, 2017. London police say they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. There are also reports of a vehicle hitting pedestrians on nearby Westminster Bridge. (AP Photo/Matt Dunham)
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In this image taken from video emergency personnel gather around a body on the southside of Westminster Bridge that leads to the Houses of Parliament in London, Wednesday, March 23, 2017 after the House of Commons sitting was suspended as witnesses reported sounds like gunfire outside. The leader of Britain's House of Commons says a man has been shot by police at Parliament. David Liddington also said there were "reports of further violent incidents in the vicinity." (ITN via AP)
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In this image taken from video police officers gather around a car adjacent to Houses of Parliament in London, Wednesday, March 23, 2017 after the House of Commons sitting was suspended as witnesses reported sounds like gunfire outside. The leader of Britain's House of Commons says a man has been shot by police at Parliament. David Liddington also said there were "reports of further violent incidents in the vicinity." (ITN via AP)
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epa05863732 Armed police following major incidents outside the Houses of Parliament in central London, Britain 22 March 2017. Scotland Yard said on 22 March 21017 the police were called to a firearms incident in the Westminister palace grounds and on Westminster Bridge amid reports of several people injured in central London. EPA/WILL OLIVER
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Emergency services at the scene outside the Palace of Westminster, London, Wednesday, March 22, 2017. London police say they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." The Metropolitan Police says in a statement that the incident is ongoing. It is urging people to stay away from the area. Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. Nearby, witnesses say a vehicle struck several people on the Westminster Bridge. (Stefan Rousseau/PA via AP).
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Emergency services staff provide medical attention close to the Houses of Parliament in London, Wednesday, March 22, 2017. London police say they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." The Metropolitan Police says in a statement that the incident is ongoing. Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. Nearby, witnesses say a vehicle struck several people on the Westminster Bridge. (AP Photo/Matt Dunham)
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epa05863751 Armed police following major incidents outside the Houses of Parliament in central London, Britain 22 March 2017. Scotland Yard said on 22 March 21017 the police were called to a firearms incident in the Westminister palace grounds and on Westminster Bridge amid reports of several people injured in central London. EPA/ANDY RAIN
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Emergency services staff provide medical attention close to the Houses of Parliament in London, Wednesday, March 22, 2017. London police say they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. There are also reports of a vehicle hitting pedestrians on nearby Westminster Bridge. (AP Photo/Matt Dunham)
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epa05863910 Armed police react following a suspected terror attack outside parliament in London, Britain 22 March 2017. Scotland Yard said on 22 March 2017 the police were called to a firearms incident in the Westminister palace grounds and on Westminster Bridge amid reports of at least two people killed and several other people injured in central London. EPA/ANDY RAIN
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epaselect epa05863794 Armed police following major incidents outside the Houses of Parliament in central London, Britain, 22 March 2017. Scotland Yard said on 22 March 21017 the police were called to a firearms incident in the Westminister palace grounds and on Westminster Bridge amid reports of several people injured in central London. EPA/WILL OLIVER
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Armed police outside the the Houses of Parliament, London, Wednesday, March 22, 2017. London police say they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." The Metropolitan Police says in a statement that the incident is ongoing. It is urging people to stay away from the area. Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. Nearby, witnesses say a vehicle struck several people on the Westminster Bridge. (Stefan Rousseau/PA via AP).
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epa05864015 Armed police following major incidents in Westminster Bridge in central London, Britain, 22 March 2017. Scotland Yard said on 22 March 21017 the police were called to a firearms incident in the Westminister palace grounds and on Westminster Bridge amid reports of at least two people killed and several other people injured in central London. EPA/FACUNDO ARRIZABALAGA
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epa05864276 Forensic experts at work following major incidents on Westminster Bridge in central London, Britain, 22 March 2017. Scotland Yard said on 22 March 2017 the police were called to a firearms incident in the Westminister palace grounds and on Westminster Bridge amid reports of at least four people killed, including the attacker, and several other people injured in central London. EPA/FACUNDO ARRIZABALAGA
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An attacker is treated by emergency services outside the Houses of Parliament in London, Wednesday, March 22, 2017. London police say they are attending a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. In another incident witnesses say a vehicle struck several people on the Westminster Bridge. (Stefan Rousseau/PA via AP)
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People stand near a crashed car and an injured person lying on the ground, right, on Bridge Street near the Houses of Parliament in London, Wednesday, March 22, 2017. Britain has been targeted Wednesday by what authorities are calling a terrorist incident, after vehicle mowed down pedestrians on London's Westminster Bridge, killing at least one woman and leaving others injured, around the same time as a knife-wielding attacker stabbed a police officer and was shot on the grounds outside Britain's Parliament. (James West via AP) Mandatory credit
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epa05864367 General view of Westminster following a terror attack in London, Britain 22 March 2017. Scotland Yard said on 22 March 2017 the police were called to a firearms incident in the Westminister palace grounds and on Westminster Bridge amid reports of at least four people killed, including the attacker, and several other people injured in central London. cs EPA/ANDY RAIN
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The River Thames backdropped by the Houses of Parliament and Elizabeth Tower containing the bell know as "Big Ben" in London, Wednesday, March 22, 2017. London police say they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." The Metropolitan Police says in a statement that the incident is ongoing. It is urging people to stay away from the area. Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. Nearby, witnesses say a vehicle struck several people on the Westminster Bridge. (AP Photo/ Matt Dunham)
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Two policemen stand guard at a cordoned off area on the way to the Houses of Parliament in central London, Wednesday, March 22, 2017. London police say they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." The Metropolitan Police says in a statement that the incident is ongoing. It is urging people to stay away from the area. Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. Nearby, witnesses say a vehicle struck several people on the Westminster Bridge. (AP Photo/ Matt Dunham)
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epa05864447 Emergency response workers continue to work over night following major incidents in Westminster Bridge in central London, Britain, 22 March 2017.. Scotland Yard said on 22 March 2017 the police were called to a firearms incident in the Westminister palace grounds and on Westminster Bridge amid reports of at least four people killed, including the attacker, and several other people injured in central London. EPA/FACUNDO ARRIZABALAGA
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epa05864448 Emergency response workers continue to work over night following major incidents in Westminster Bridge in central London, Britain, 22 March 2017. Scotland Yard said on 22 March 2017 the police were called to a firearms incident in the Westminister palace grounds and on Westminster Bridge amid reports of at least four people killed, including the attacker, and several other people injured in central London. EPA/FACUNDO ARRIZABALAGA
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Britain's Prime Minister Theresa May gives a media statement outside 10 Downing street in London, Wednesday March 22, 2017, following a terror attack in the Westminster area of London earlier Wednesday. A knife-wielding man went on a deadly rampage, Wednesday, plowing a car into pedestrians on London's Westminster Bridge before stabbing an armed police officer to death inside the gates of Parliament. Four people were killed, including the attacker, and about 20 others were injured in what authorities called a terrorist incident. (Richard Pohle/Pool via AP Photo)
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