see more

LONDON, ENGLAND - MARCH 23: Police forensic officers work on Westminster Bridge following yesterday's attack, on March 23, 2017 in London, England. Four people have been killed and around 40 people injured following yesterday's attack by the Houses of Parliament in Westminster. (Photo by Carl Court/Getty Images)

LONDON, ENGLAND - MARCH 23:  Police forensic officers work on Westminster Bridge following yesterday's attack, on March 23, 2017 in London, England. Four people have been killed and around 40 people injured following yesterday's attack by the Houses of Parliament in Westminster.  (Photo by Carl Court/Getty Images)

see more

LONDON, ENGLAND - MARCH 23: Police officers stand on Westminster Bridge as it is closed following yesterday's attack. on March 23, 2017 in London, England. Four people have been killed and around 40 people injured following yesterday's attack by the Houses of Parliament in Westminster. (Photo by Carl Court/Getty Images)

LONDON, ENGLAND - MARCH 23: Police officers stand on Westminster Bridge as it is closed following yesterday's attack. on March 23, 2017 in London, England. Four people have been killed and around 40 people injured following yesterday's attack by the Houses of Parliament in Westminster.  (Photo by Carl Court/Getty Images)

see more

LONDON, ENGLAND - MARCH 23: Police officers stand on Westminster Bridge as it is closed following yesterday's attack. on March 23, 2017 in London, England. Four people have been killed and around 40 people injured following yesterday's attack by the Houses of Parliament in Westminster. (Photo by Carl Court/Getty Images)

LONDON, ENGLAND - MARCH 23:  Police officers stand on Westminster Bridge as it is closed following yesterday's attack. on March 23, 2017 in London, England. Four people have been killed and around 40 people injured following yesterday's attack by the Houses of Parliament in Westminster.  (Photo by Carl Court/Getty Images)

see more

British counter-terrorism police officers carry their weapons as they work on Westminster Bridge, adjacent to the Houses of Parliament in central London on March 22, 2017, during an emergency incident. British police shot a suspected attacker outside the Houses of Parliament in London on Wednesday after an officer was stabbed in what police said was a 'terrorist' incident. One woman has died and others have 'catastrophic' injuries following a suspected terror attack outside the British parliament, local media reported on Wednesday citing a junior doctor. / AFP PHOTO / Daniel LEAL-OLIVAS (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)

British counter-terrorism police officers carry their weapons as they work  on Westminster Bridge, adjacent to the Houses of Parliament in central London on March 22, 2017, during an emergency incident.
British police shot a suspected attacker outside the Houses of Parliament in London on Wednesday after an officer was stabbed in what police said was a 'terrorist' incident. One woman has died and others have 'catastrophic' injuries following a suspected terror attack outside the British parliament, local media reported on Wednesday citing a junior doctor. / AFP PHOTO / Daniel LEAL-OLIVAS        (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)

see more

Armed police officers carry their weapons as forensics officers work near a grey vehicle that crashed into the railings of the Houses of Parliament in central London on March 22, 2017, during an emergency incident. British police shot a suspected attacker outside the Houses of Parliament in London on Wednesday after an officer was stabbed in what police said was a 'terrorist' incident. One woman has died and others have 'catastrophic' injuries following a suspected terror attack outside the British parliament, local media reported on Wednesday citing a junior doctor. / AFP PHOTO / Daniel LEAL-OLIVAS (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)

Armed police officers carry their weapons as forensics officers work near a grey vehicle that crashed into the railings of the Houses of Parliament in central London on March 22, 2017, during an emergency incident.
British police shot a suspected attacker outside the Houses of Parliament in London on Wednesday after an officer was stabbed in what police said was a 'terrorist' incident. One woman has died and others have 'catastrophic' injuries following a suspected terror attack outside the British parliament, local media reported on Wednesday citing a junior doctor. / AFP PHOTO / Daniel LEAL-OLIVAS        (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)