Police have identified the suspect in a stabbing attack Friday in London as 28-year-old Usman Khan saying, "as a result, officers are, tonight, carrying out searches at an address in Staffordshire."

According to UK police, Khan was convicted in 2012 on terrorism offences. Metropolitan Police said in a tweet that Khan "was released from prison in December 2018 on licence and clearly, a key line of enquiry [sic] now is to establish how he came to carry out this attack." 

A man wearing a fake explosive vest stabbed several people Friday in London, killing two in what police are treating as a terrorist attack, before being tackled by members of the public and then fatally shot by officers on London Bridge, officials said.

Metropolitan Police said in a statement Friday, "a male suspect was shot by specialist armed officers and I can confirm that he died at the scene. We are now in a position to confirm the identity of the suspect as 28-year-old Usman Khan"

Metropolitan Police Chief Cressida Dick said two stabbing victims have died and three injured people were being treated in a hospital.

She said police were working “at full tilt” to determine whether anyone else was involved in the attack.

The violence erupted two-and-a-half years after a van and knife attack in the same area killed eight people, and less than two weeks before Britain holds a national election. The main political parties temporarily suspended campaigning in London as a mark of respect.

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Prime Minister Boris Johnson’s office said it would chair a meeting of the government’s emergency committee, COBRA, later Friday evening.

Metropolitan Police counterterrorism chief Neil Basu said the suspect appeared to be wearing a bomb vest but it turned out to be “a hoax explosive device."

Basu said officers were keeping “an open mind as to any motive.”

Dick, the police chief, said officers were called just before 2 p.m. to Fishmongers’ Hall, a conference venue at the north end of London Bridge. The pedestrian and vehicle bridge links the city’s business district with the south bank of the River Thames. 

Police said Friday in a statement, "the circumstances, as we currently understand them, are that the attacker attended an event earlier on Friday afternoon at Fishmonger’s Hall called ‘Learning Together’. We believe that the attack began inside before he left the building and proceeded onto London Bridge, where he was detained and subsequently confronted and shot by armed officers."

Cambridge-based prison-education organization Learning Together was holding an event there Friday, and the University of Cambridge said it was “gravely concerned” about students, staff and alumni who might have been caught up in the attack.

Minutes after the stabbings report, witnesses saw a knifeman being wrestled to the ground by members of the public on the bridge before armed-response officers shot him dead.

One video posted on social media showed two men struggling on the bridge before police pulled a man in civilian clothes off a black-clad man on the ground. Gunshots followed. Another depicted a man in suit and overcoat holding a long knife that apparently had been taken from the attacker.

The mayor praised the “breathtaking heroism of members of the public who literally ran towards danger not knowing what confronted him.”

“They are the best of us,” Khan said.

The prime minister also praised the bystanders, and said anyone who was involved in the attack “will be hunted down and will be brought to justice.”

Cars and buses on the busy bridge were at a standstill after the shooting, with a white truck stopped diagonally across the lanes. Video footage showed police pointing guns at the truck before moving to check its container.

London Bridge station, one of the city’s busiest rail hubs, was closed for several hours after the attack.

Scores of police, some armed with submachine guns, flooded the area, ushering office workers and tourists out of the area, which is packed with office buildings, banks, restaurants and bars. Staff in nearby office blocks were told to stay inside.

As police cleared the streets, staff in shops and restaurants ushered customers into storerooms and basements. Some had been through similar traumatic events: In June 2017, eight people died in a van and knife attack in the same area.

In that attack, three assailants inspired by the Islamic State group ran down people on the bridge, killing two, before stabbing several people to death in nearby Borough Market.

The 2017 fatal attack took place days before a general election. Britons are due to go to the polls again on Dec. 12.

Political leaders expressed shock and sorrow at Friday’s attack.

“We will not be cowed by those who threaten us,” Labour Party leader Jeremy Corbyn said. “We must and we will stand together to reject hatred and division."

Both Labour and the Conservatives suspended campaigning in the city after the attack and the prime minister was also canceling political events for Saturday.

Another London bridge was the target of an attack in March 2017, when attacker killed four people with a car on Westminster Bridge then fatally stabbed a police officer before security forces shot and killed him in a courtyard outside Parliament.

Security officials earlier this month downgraded Britain's terrorism threat level from "severe" to "substantial," which means an attack is seen as "likely" rather than "highly likely." The assessment was made by the Joint Terrorism Analysis Centre, an independent expert body that evaluates intelligence, terrorist capability and intentions.

The U.K.'s terror threat was last listed as "substantial" in August 2014; since then it has held steady at "severe," briefly rising to "critical" in May and September 2017.