British Prime Minister Theresa May said Monday that police know the identities of the three attackers who killed seven people and wounded more than 50 others Saturday in London.
May said their names would be released "when progress in the investigation permits," and that authorities were holding 11 people in custody in connection with the probe.
She said police are also still working to determine the identities of all the victims, but that so far it is known they include people of several nationalities.
"This was an attack on London and the United Kingdom, but it was also an attack on the free world," she said.
London police carried out more raids Monday and detained "a number" of people during searches at locations in the Newham and Barking areas.
Police have said Saturday's attack involved three men who were inside a van that struck pedestrians on London Bridge, then got out and stabbed numerous people at a nearby market area before being shot dead by police.
"We are trying to find out whether anybody was helping them and to understand the background to this attack as best as we possibly can," Metropolitan Police Commissioner Cressida Dick told Sky News.
The Islamic State group claimed responsibility for the attack through its Amaq news agency.
May said Sunday that three terrorist attacks in Britain in the last three months are "bound together by the evil ideology of Islamist extremism."
There is "far too much tolerance for extremism in our country," May said. "We need to be more robust in identifying and stamping out extremism in public service and across society...it's time to say enough is enough."
May said Saturday's attack does not appear to be connected to the a suicide bombing last month that killed 22 people after an Ariana Grande concert in Manchester or another attack on pedestrians on Westminster Bridge in March.
But she said "terrorism breeds terrorism" and that the perpetrators are "copying one another."
London Mayor Sadiq Khan condemned the attack saying, "There is no justification whatsoever for such barbaric acts."
Farhad Ahmad, a London Imam, told Sky News "people need to be told that there is no support for this in Islam at all."
Bahrain, Kuwait, Oman, Qatar and the United Arab Emirates each issued statements condemning the attack and expressing support for Britain.
At a Mass marking Pentecost, the end of the Easter season, Pope Francis asked for prayers for the victims and their families. He also prayed for "peace to the whole world" and for the wounds of war and terrorism to be healed.
Before their Champions Trophy match in Birmingham, rival cricket teams from India and Pakistan observed a moment of silence for the victims.
A moment of silence also was held in Manchester, where American pop singer Ariana Grande returned to headline an all-star concert to raise money for the victims of the May 22 suicide bombing.
Fifty-thousand people, including some who were wounded in the concert attack, attended the show, which raised more than $2.5 million.
President Donald Trump offered America’s “full support” in investigating the “brutal terror attacks” in London during a telephone call with Prime Minister May.
Whatever the United States can do to help out in London and the U. K., we will be there - WE ARE WITH YOU. GOD BLESS!— Donald J. Trump (@realDonaldTrump) June 3, 2017
The U.S. Department of Homeland Security said it was in close contact with British authorities.
“At this time,” an official statement said, “we have no information to indicate a specific, credible terror threat in the United States” as a result of the London attack.
President Trump also tweeted that the attacks emphasized the correctness of his strict policies on immigration. Other users of social media, both in the U.S. and in Britain, criticized Trump.