Armed police responded to the incident at London Bridge on Friday (Picture: PA).
The London Bridge attacker was a convicted terrorist released halfway through a 16-year prison sentence for a plot to bomb the London Stock Exchange.
Usman Khan, 28, killed two people in the knife rampage on Friday afternoon and injured three others. Two are still being treated in hospital; one has been discharged.
Khan was attending a conference on prisoner rehabilitation at Fishmongers' Hall, organised by the University of Cambridge-associated Learning Together. He "threatened to blow up" the building just before 2pm.
Armed with two knives and wearing a fake suicide vest, Khan was tackled by members of the public - including one with a narwhal tusk - before he was shot dead by police on London Bridge.
Metropolitan Police Assistant Commissioner Neil Basu said that Khan had been living in the Staffordshire area and that police were "not actively seeking anyone else" over the attack.
On Saturday morning, uniformed officers were standing guard outside a three-storey block of flats in Wolverhampton Road, Stafford, where a property was being searched.
In February 2012, Khan, who had been based in Stoke-on-Trent, was handed an indeterminate sentence for public protection over his part in an al-Qaeda-inspired terror group that plotted to bomb the London Stock Exchange and build a terrorist training camp on land in Pakistan-controlled Kashmir owned by his family.
A list of his other potential targets included the names and addresses of the Dean of St Paul's Cathedral in London, then London mayor Boris Johnson, two rabbis, and the American Embassy in London.
But the sentence for Khan, along with two co-conspirators, was quashed at the Court of Appeal in April 2013 and he was given a determinate 16-year jail term.
Prisoners are usually released halfway through a determinate sentence, but Khan had served less than seven years when he was freed on licence in December 2018.
His time spent in custody before he was sentenced may have been taken into account.
The Parole Board said it had no involvement in his release and that Khan "appears to have been released automatically on licence (as required by law), without ever being referred to the board".
Speaking before chairing a meeting of the Government's emergency committee, Cobra, on Friday night, Prime Minister Boris Johnson said he had "long argued" that it is a "mistake to allow serious and violent criminals to come out of prison early and it is very important that we get out of that habit and that we enforce the appropriate sentences for dangerous criminals, especially for terrorists, that I think the public will want to see".
WATCH: London Bridge eyewitness recalls seeing man being 'wrestled to the floor'.
Members of the public who intervened to stop the attacker have been widely praised, with Mayor of London Sadiq Khan hailing their "breathtaking heroism" and Mr Johnson their "extraordinary bravery".
Video footage posted online shows Khan being taken to the ground as one man sprays him with a fire extinguisher and another lunges towards him with a narwhal tusk, believed to have been taken from the wall inside Fishmongers' Hall.
The Metropolitan Police have named the man and woman who died in the terrorist attack near London Bridge on Friday as Jack Merritt, 25, of Cottenham, Cambridgeshire, and Saskia Jones, 23, of Stratford-upon-Avon, Warwickshire.
The attack came weeks after the UK's terrorism threat level was downgraded to "substantial" from "severe", meaning attacks were thought to be "likely" rather than "highly likely".
Home Secretary Priti Patel made the announcement on 4 November, days after Parliament voted to hold an early election.
London Bridge was the scene of a terror attack in 2017, when eight people were killed along with the three terrorists, who were also wearing fake suicide vests and armed with knives.