The attacker who killed three people in Westminster has been named by police as Khalid Masood, who was once investigated by MI5 intelligence officers.
Kent-born Masood, who was shot dead in the attack, was not the subject of any current police investigations, but had a range of previous convictions.
The 52-year-old was believed to have been living in the West Midlands.
The so-called Islamic State group has said it was behind the attack, in which PC Keith Palmer, Aysha Frade and US tourist Kurt Cochran were killed.
Police arrested eight people at six locations in London and Birmingham in the investigation into the attack.
All were suspected of preparing terrorist acts, police later confirmed.
Prime Minister Theresa May earlier told parliament the attacker had once been investigated by the MI5 intelligence agency over concerns about violent extremism, but was a peripheral figure.
Police said there had been no prior intelligence about Masood's intention to carry out an attack. However he was known to the police and his previous convictions included grievous bodily harm, possession of offensive weapons and public order offences.
His first conviction was in November 1983 for criminal damage and his last conviction was in December 2003 for possession of a knife.
He had not been convicted of any terrorism offences.
Mrs May has visited a hospital where she spoke to victims of the attack near parliament as well as hospital staff,
About 40 people were injured in the attack, of whom 29 remain in hospital, seven in critical condition.
- BBC / Reuters