Three terrorists were shot dead in a hail of gunfire by armed police officers after they stabbed members of the public on Saturday night near London Bridge.
Seven people were killed by the extremist trio, and a further 21 are in a critical condition following the terror attack in Britain’s capital.
A Canadian national was among those killed, while citizens of Britain, France, Australia and New Zealand were caught up in the atrocity.
Eight armed officers fired an “unprecedented” volley of bullets at the three attackers, Assistant Commissioner Mark Rowley said.
“Our initial assessment is in the region of 50 rounds – in the region of 50 bullets – were fired by those eight officers,” he said.
“The three attackers were shot dead. The situation these officers were confronted with was critical – a matter of life and death – three armed men wearing what appeared to be suicide belts.”
He said a member of the public was accidentally shot, but their condition is non-critical.
London’s Metropolitan Police later swooped to arrest 12 people in Barking, east London, in connection with the attack.
Downing Street announced the UK will observe a minute’s silence on Tuesday June 6 at 11am in remembrance of those who lost their lives and all others affected by the atrocity.
UK to observe a minute‘s silence at 11am on Tuesday 6 June for victims of the London terrorist attack https://t.co/qZapxoVaQi— UK Prime Minister (@Number10gov) June 4, 2017
The attack comes less than two weeks after a suicide bomber killed 22 people at an Ariana Grande concert in Manchester and three months after a terrorist killed six in Westminster.
A British Transport Police officer, who was armed with just his baton, and an off-duty Metropolitan Police officer were among around 50 people injured as the trio rampaged through a busy area of the capital armed with foot-long knives after mowing down pedestrians in a van.
Eyewitnesses said the men were shouting “This is for Allah” as they went on the rampage, stabbing men and women enjoying a Saturday night out.
They were killed by police at nearby Borough Market within eight minutes of the first call being made at 10.08pm (BST).
Mayor of London Sadiq Khan said: “This was a deliberate and cowardly attack on innocent Londoners and visitors to our city enjoying their Saturday night.
“I condemn it in the strongest possible terms. There is no justification whatsoever for such barbaric acts.”
My statement on the cowardly terrorist attack in London tonight: https://t.co/7GYYdImIU8
Please continue to follow
metpoliceuk</a> for updates <a href="https://t.co/xxTbH2o2JN">pic.twitter.com/xxTbH2o2JN</a></p>— Sadiq Khan (SadiqKhan) June 4, 2017
The attacks came just five days ahead of the General Election on Thursday, which will go ahead as planned.
The area remained cordoned off on Sunday, with train stations closed.
Forensic investigators could be seen working on the bridge, where buses and taxis stood abandoned.