A 75-year-old man has become the fourth innocent victim to die following the horrifying terror attack in Westminster.
The man, who has not been named, died after life support was withdrawn at King's College Hospital on Thursday night.
His death was announced as more information emerged about Khalid Masood, the man who drove at pedestrians on Westminster Bridge before crashing his hire car and stabbing to death Pc Keith Palmer at the gates to the Houses of Parliament.
Scotland Yard said Masood - who was shot dead by police - was born in Kent on Christmas Day in 1964.
Police said they did not believe Masood was his birth name but refused to comment on reports that he was born Adrian Elms.
A spokesman said Masood, 52, was known by a number of aliases and research into them was continuing.
Scotland Yard said Masood, who was most recently thought to be living in the West Midlands, was not the subject of any current investigations before Wednesday's outrage and there was "no prior intelligence about his intent to mount a terrorist attack".
But he was known to police and MI5 and had convictions for assaults, including GBH, possession of offensive weapons and public order offences.
Masood's victims on Westminster Bridge included a US tourist from Utah who was celebrating his wedding anniversary and a "highly regarded and loved" member of college staff.
Kurt Cochran and his wife Melissa, on the last day of a trip celebrating their 25th anniversary, were visiting her parents, who are serving as Mormon missionaries in London.
Mrs Cochran was badly injured.
Aysha Frade, who worked in administration at independent sixth-form school DLD College London, in Westminster, is understood to have been 43 and married with two daughters.
The family of the 75-year-old man who died on Thursday was receiving support from specially-trained liaison officers, Scotland Yard said.
Up to 40 other people were also injured in the attack, with casualties including Britons, French children, Romanians, South Koreans, Greeks, and people from Germany, Poland, Ireland, China, Italy and the United States.
Three police officers were also hurt, two of them seriously.
Police arrested three women and five men on suspicion of preparing terrorist acts after raids in London and Birmingham.
A house in Carmarthenshire, south-west Wales, was also searched, Dyfed-Powys Police said.
The force said in a statement: "The occupants are receiving appropriate support. They are not suspects and have not been arrested.
"There is no threat to the area and we are supporting the broader investigation by the MPS Counter Terrorism Command."
A minute's silence was held nationwide on Thursday and crowds later gathered in Trafalgar Square for a candlelit vigil.
Prime Minister Theresa May told MPs who gathered inside the Palace of Westminster that Pc Palmer "was every inch a hero and his actions will never be forgotten".
The officer's family described him as "brave and courageous".
Mrs May said Masood was investigated some years ago in relation to concerns about violent extremism but was a "peripheral figure".
Home Secretary Amber Rudd defended the security and intelligence agencies, saying: "The fact that he was known to them doesn't mean that somebody has 24-hour cover."
She disclosed Masood had spent time in jail, but said it was not for terrorist-related offences.
As police and intelligence agencies mounted a massive investigation to piece together the killer's movements in the lead-up to the attack:
Searches were carried out at three addresses in Birmingham and one each in east London, Brighton, south-east London and Carmarthenshire.
The Sun reported that Masood stayed in the Preston Park Hotel in Brighton the night before the attack.
Hotel staff told the Press Association they had been instructed not to talk.
The Islamic State terror group claimed in a statement that the attacker was "a soldier of the Islamic State executing the operation in response to calls to target citizens of coalition nations".
Commentators pointed out the group had a record of opportunistically claiming attacks and it was significant the statement did not appear to claim it had directed the strike.
Carriage Gates, where Pc Palmer and Masood died, was back in use on Thursday evening, although armed police were at the entrance.
Roads around the Palace of Westminster, including Parliament Square, also reopened.