WARNING: Graphic content
The terrorist who killed two people at London Bridge and injured several others before being shot dead by police has been named as Usman Khan.
Khan was jailed in 2012 for his role in the Stock Exchange terror plot which was disrupted by MI5 and police. Authorities have confirmed he was still wearing an electronic tag as per his parole conditions.
In a bizarre development, it has emerged that Khan may have attended a story telling and creative workshop at Fishmongers' Hall just moments before he threatened to blow up the venue, reports News.com.au.
Ironically the University of Cambridge-organised conference was on prisoner rehabilitation.
University Vice-Chancellor Professor Stephen Toope said he was "devastated" that an event organised by its Institute of Criminology was targeted in the attack.
"I am devastated to learn that today's hateful attack on London Bridge may have been targeted at staff, students and alumni attending an event organised by the University of Cambridge's Institute of Criminology," he said.
"We are in touch with the Metropolitan Police, and awaiting further details of the victims.
"We mourn the dead and we hope for a speedy recovery for the injured. Our thoughts are with all their families and friends."
London's Metropolitan Police said they were called to a stabbing near London Bridge at 1.58pm on Friday (1am Saturday AEDT).
A man and a woman are believed to have been killed and three other people were taken to hospital by ambulance.
Assistant Commissioner Neil Basu confirmed a male suspect was shot by an officer during the incident and he died at the scene. He was shot in full view of horrified onlookers.
The whole incident was over within five minutes of police receiving the first report.
According to The Times, the suspect was a guest at a Cambridge University conference on prisoner rehabilitation when he threatened to blow up the historic Fishmongers' Hall.
He was wearing a fake suicide vest and had two knives in his possession when he carried out the attack.
The program for the Learning Together event, organised by the University's Institute of Criminology shows attendees enjoyed a "brunch and chat" between 11am and midday local time.
The convicted terrorist launched his attack halfway through an interactive workshop featuring story telling and creative writing that ran from 12.15pm to 2.15pm local time.
After threating to blow up Fishmongers' Hall, the double knife weilding Usman was reportedly chased by bystanders, including some fellow attendees onto London Bridge where he went on a stabbing rampage.
A man who grabbed an iconic narwhal tusk mounted on the wall of the hall and another armed with a fire extinguisher took Usman down with the help of tour guides Thomas Gray and Stevie Hurst.
"A number of other people received injuries at this incident," Assistant Commissioner Basu said, however he did not confirm how many.
All the casualties were taken to the Royal London hospital in Whitechapel, one of London's four designated major trauma centres, The Guardian reports.
NHS chief executive Simon Stevens confirmed two victims had died, with three more seriously injured, one of them critically.
"Our heartfelt thanks go to everyone who responded to this incident, both the extraordinarily brave members of the public and our emergency responders," Mr Stevens said.
"As the Met police have confirmed, sadly two people have died in addition to the suspect. London Ambulance Service treated people at the scene and three were taken to hospital.
"We can confirm that one patient is critical but stable, a second person is in a stable condition and a third person has less serious injuries.
"Our deep sympathies are with the families and all those affected by today's incident."
Australian Prime Minister Scott Morrison said on Twitter: "Just terrible news out of London and The Hague", referring to a second stabbing attack in The Netherlands.
"Whether it has been the despicable acts of terrorists in the UK, or as yet not determined in the Netherlands, Australians' deepest sympathies are with the victims and their families — they were innocent people going about their lives."
The man shot by police was wearing a suicide vest that police believe was a hoax however extensive police cordons remain in place in the surrounding area.
Witnesses reported hearing multiple shots fired on the bridge on Friday afternoon. Cars and buses were forced to a standstill while a white truck lay jackknifed across the stream of traffic.
Barriers put in place following a 2017 terror attack at London Bridge that killed eight people prevent vehicles being able to mount the pavement.
Video from a helicopter shows armed police swarming around the back of the truck. Other videos show a group of bystanders grappling with a person on the bridge while police surround them holding guns.
One man manages to take a large knife off the attacker and run away from the group while shots can be heard in the background.
Prime Minister Boris Johnson paid tribute to the "extraordinary bravery of members of the public who physically intervened."
"To me they represent the very best of our country and I thank them on behalf of our country," he said, adding that the perpetrators would be "hunted down and be brought to justice."
"One cannot help but think back to what happened in 2017 in the same part of the city," he said in reference to the attack that killed eight people and injured 48 after three men drove a van into pedestrians and terrorised patrons in Borough Market with knives.
London's top cop Cressida Dick described five minutes of terror as the attack unfolded at Fishmonger's Hall at 1.58pm, with the alleged terrorist taken down by 2.03pm.
She praised the civilian heroes — including one armed with a narwhal tusk and another with a fire extinguisher — who helped tackle and disarm the assailant.
"I want to thank all the emergency service personnel who are currently working tirelessly to deal with this incident, particularly the police officers from the Met and the City who have worked so closely together to protect the public," Commissioner Dick said.
"I also want to thank the members of the public who have helped, either by showing extraordinary courage by stepping in or by following the instructions they've been given by officers at the scene and in the area. This support from our public assists us more than you could know.
"In the coming days, you will see more police – both armed and unarmed – patrolling our streets to help reassure those who are understandably concerned. Similarly, our counter-terrorism detectives will be working round the clock to identify those who have lost their lives, to support all the victims and their families.
"We are also working at full-tilt to understand exactly what has happened and whether anyone else was involved. For this reason we expect cordons to remain in place around the London Bridge area for some time."
WITNESSES DESCRIBE DAYLIGHT HORROR
Witnesses reported hearing gun shots during the middle of a busy Friday afternoon.
Amanda Hunter said she was on a bus when it came to a stop.
"There was a commotion and I looked over the window and I saw three police officers running over to a man who had something in his hand, I don't know what," she said.
"I saw a police officer shoot him."
"I saw a man and three police officers trying to put him on the ground and then I heard about three shots go into the man and then police officers went away from the suspect."
One woman who didn't want to be named said: "I was just walking along the bridge and I heard four or five shots from behind me.
"I just ran. I didn't even look back. I've no idea of it was police or not. I was terrified."
Bus driver Mustafa Salih, 62, was travelling from Borough High Street towards London Bridge where he saw emergency vehicles and the police cordon.
He told BBC London: "A police officer came up to me and said turn off your engine, get off and run.
"I looked up and I could see a crowd of people coming towards me.
"One woman was crying. I ran back down to Borough High Street. It was all very scary as we did not know what was happening."
BBC reporter John McManus was in the area and said he saw figures grappling on the bridge. He said: "I thought it was initially a fight," but then shots rang out.
Guardian journalist Owen Jones said he had just cycled to the area and found police yelling "keep moving" while ushering people behind the cordon.
"It was a very tense atmosphere," he said. "You're in the middle of an urban area with police yelling keep moving … you know that something is very clearly off."
"The whole area is crawling with police. The scene is one of extreme confusion."
David Winchester, 57, who is visiting London from the US said he heard around five gunshots on London Bridge before running from the scene.
He said: "I heard five, maybe six shots, and then the screaming."
"I have no idea what it was about but everyone was screaming to run."
"There were people in tears. It was bad. You know when you just have to get out of somewhere."
Reem Yousef told Sky News: "I was below the bridge, about 30 metres to one side of it. I heard shouting.
"I looked up and it appeared to be potentially four or five people – it looked like it was a fight.
"Then I heard someone shouting 'get back, get back'.
"People started running across the bridge and then [I] heard two gunshots and at that point obviously I ran."
BUILDINGS IN LOCKDOWN
The News UK building, the Shard and others in the surrounding area have gone into lockdown. Workers from hotels were seen running from the scene as buildings were evacuated. People inside were told to stay away from the glass.
On November 4, the UK's terrorism threat level was downgraded from "severe" to "substantial", meaning that attacks were thought to be "likely" rather than "highly likely".
UK Home Secretary Priti Patel briefed Prime Minister Boris Johnson on the situation. In the aftermath of the attack she tweeted: "Very concerned by ongoing incident at London Bridge. My thoughts are with all affected."
"I am grateful for the rapid response of our police and I urge everyone to follow their advice."
London Mayor Sadiq Khan thanked emergency services for their response and said Londoners would "stay resolute and united in the face of terror."
"It shows the breathtaking heroism of members of the public who literally ran towards danger not knowing what was in front of them," he said
"Members of the public didn't know it was a hoax at the time … it shows the best of us."
Labour leader Jeremy Corbyn said: "Shocking reports from London Bridge. My thoughts are with those caught up in the incident. Thank you to the police and emergency services who are responding."
London Bridge was the scene of a terror attack in June 2017 in which three people drove a van into pedestrians and went on a stabbing rampage in Borough Market. Eight people were killed including two Australians, with 48 injured. The three attackers were shot dead by police.
The UK also suffered recent terror attacks in Westminster, where an attacker killed four pedestrians and one police officer in March 2017, as well as at an Ariana Grande concert in May 2017 where 23 people were killed including the perpetrator.