British police identified the man suspected of killing two people in a terrorist attack near London Bridge on Friday as 28-year-old Usman Khan.

Khan was convicted in 2012 for terrorism offenses and had been living in the Staffordshire area after he was released from prison last year with an ankle monitor, Metropolitan Police Assistant Commissioner Neil Basu said in a statement.

Police say Usman Khan, 28, is the suspect in Friday's attack in London.

Basu said authorities are not "actively seeking anyone else in relation to the attack."

Police officers shot and killed Khan after two people were stabbed to death, and at least three others were injured during the attack on Friday, London Metropolitan Police said. The suspect had a fake bomb strapped to him when he was shot, police said.

Speaking before a meeting of the UK government's emergency response committee Cobra on Friday night, British Prime Minister Boris Johnson said it was important to enforce appropriate prison sentences for criminals.

"I have long argued that it is a mistake to allow serious and violent criminal 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 terrorists," he said in a pool interview.

The rampage began just before 2 p.m. at Fishmonger's Hall, a historic building on the north side of the London Bridge. The suspect was attending an event in the building organized by the University of Cambridge's Institute of Criminology, according to the assistant commissioner and the organizer's website.

"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," Basu said.

Video filmed by a bystander shows a man being wrestled to the ground by several bystanders on the northern end of the bridge, shortly after police were called to Fishmonger's Hall.

Tom Gray, a tour guide who tried to apprehend the suspect, told CNN affiliate ITV that the attacker was "wielding two knives, one was duct taped to his hand." After other bystanders had held the suspect down, Gray said he tried to "stamp the other knife from his wrist" and then kicked it further down the bridge.

Lloyd Griffiths, 35, who was on a bus on the bridge, said he saw the attacker had a large blade.

"I saw a shine on a knife or metal blade, it was startling. It was large blade, it wasn't small, and then I was locked on the bus, people tried to tackle to man trying to fight him, ordinary people jumping out of the car, trying to fight him," Griffiths said.

"Then police ran over with guns, screaming," before shooting the man, Griffiths added. Multiple emergency vehicles quickly arrived on the scene as crowds of people fled the area.

A man and woman were killed in the attack on Friday, Basu said in a statement early on Saturday. Three others, a man and two women, were injured and remained hospitalized. None of the victims have been named.

Authorities have not discussed the motive for the attack but earlier on Friday, Basu said it had been declared as a terrorist incident.

"I must stress, however, that we retain an open mind as to any motive. It would not be appropriate to speculate further at this time," Basu told reporters Friday afternoon.

In the wake of the attack, Metropolitan Police Commissioner Cressida Dick said officials decided to enhance patrols, including armed and unarmed officers, in the area and across the city and are encouraging residents to cooperate with police.

"Fighting terrorism takes effort and determination from all of us. If you have any information or concerns, please do contact us," Dick said. "The empty ideology of terror offers nothing but hatred and today I urge everyone to reject that. Ours is a great city because we embrace each other's differences, we must emerge strong and still from this tragedy."