Prime Minister Theresa May came under intense pressure on Monday over her record on security after a third terror attack in three months killed seven people just days ahead of a general election.
The aftermath of Saturday night's rampage grew intensely political ahead of the vote on Thursday, with opposition Labour leader Jeremy Corbyn saying he would support calls for May to resign over the sharp reduction in police numbers during her six years interior minister from 2010.
Police also carried out fresh raids and made further arrests after the Islamic State group claimed the attack by three men wearing fake suicide vests who mowed down and stabbed revellers.
No details have been released about the perpetrators, who were shot dead within eight minutes of the first call to the police. "A number of people have been detained," police said in a statement after two early morning raids in east London. Another 11 people are also being held in custody.
The row over policing erupted as campaigning for the election resumed after being suspended for a day out of respect for the victims. "We should never have cut the police numbers," Corbyn said. May insisted London police were happy with their resources, while counter-terrorism budgets had been protected and the number of armed officers increased.
The capital's police chief Cressida Dick and Mayor Sadiq Khan visited London Bridge on Monday, as commuters returned to the scene of the attacks after some security cordons were removed. "A very high priority for us is to try to understand whether they were working with anybody else," Dick told BBC television.
She said police had seized "a huge amount of forensic material" after examining the white van used in the attack. "We will change and adapt to what appears to be a new reality for us," she said. Khan, a practising Muslim, said the attackers' ideology was "perverse, it is poisonous and it has no place in Islam".
May blamed "evil" Islamist ideology and vowed to crack down on extremist content online, warning that attackers were "copying one another". She said the same ideology was behind the May 22 Manchester suicide bombing at a pop concert that left 22 people dead, and the Westminster Bridge attack in March, which killed five.
The Islamic State group claimed responsibility for Saturday's carnage. "A detachment of fighters from Islamic State carried out London attacks," said the Amaq news agency, which is affiliated with the jihadists. The victims included 48 people treated in hospital for injuries. Of those, 21 are still in a critical condition.
A Canadian and a Frenchman were among the fatalities and citizens of several nations were among the injured, including Australia, Bulgaria, France and New Zealand. French Foreign Minister Jean-Yves Le Drian was due to visit Britain on Monday to speak to the injured French nationals.
The assailants ran people over on London Bridge before lunging seemingly at random at crowds gathered around Borough Market, which is full of restaurants and bars.
Eight officers fired an "unprecedented" 50 rounds at the three attackers, according to Mark Rowley, head of national counter-terrorism policing, who said a bystander had also suffered a gunshot wound. Gerard Vowls, 47, said he saw a woman repeatedly stabbed, and threw chairs, glasses and bottles at the attackers in a bid to stop them.
"They kept coming to try to stab me… they were stabbing everyone. Evil, evil people," he told The Guardian newspaper. Another witness called Eric told the BBC he had seen three men get out of the van who took out knives.
"It was a rampage," he said, adding that he heard a shout of: "This is for Allah". Among those stabbed was an unarmed off-duty police officer who rushed to confront the attackers. Police chief Dick called his actions "heroic". A vigil for the victims will take place at nearby Tower Bridge on Monday evening.
Britain was already on high alert following the attack on a concert by US pop star Ariana Grande in Manchester, northwest England, in which seven children were among the 22 dead. Grande headlined a benefit concert in Manchester on Sunday, alongside stars including Pharrell Williams and Justin Bieber.
The national threat level was raised to maximum after the Manchester attack and troops were deployed at key public sites, but reduced to its second-highest level last weekend. May said Britain's response to the terror threat must change.
"We cannot and must not pretend that things can continue as they are," she said, adding there was "far too much tolerance of extremism in our country". Saturday's rampage was the latest in a string of attacks to hit Europe, including in Paris, Berlin and Saint Petersburg, and the US, French, German and Russian leaders sent messages of support.
