Police now say at least seven people have died and dozens of others have been injured in attacks on London Bridge and in Borough Market. Three attackers in a van mowed down pedestrians before starting a stabbing spree.
Below, read DW's live updates from just after the attack on London Bridge on Saturday night through to 12 people being arrested on Sunday.
What we know so far:
Three attackers then began stabbing people in the Borough Market area, which is located near London Bridge. The assailants were shot dead by police. They were wearing fake suicide vests.
Police said at least seven victims have died and dozens of others have been wounded. An officer from the British Transport Police was among those seriously injured.
All updates in Universal Coordinated Time (UTC).
14:27 After Trump took to Twitter to criticize London Mayor Sadiq Khan the mayor's office made a brief statement.
"The Mayor is busy working... to coordinate the response to this horrific and cowardly terrorist attack," said Khan's spokesman. "He has more important things to do than respond to Donald Trump's ill-informed tweet that deliberately takes out of context his remarks urging Londoners not to be alarmed when they saw more police -- including armed officers -- on the streets."
14:24 The German foreign ministry says German citizens are among those wounded in the attack, including one person severely injured.
12:45 US President Donald Trump on Twitter criticizes London Mayor Sadiq Khan for saying there is "no reason to be alarmed." He also uses the London attacks to promote gun rights in the United States and slams political correctness.
"The investigation into last night's horrific attack in London is progressing rapidly as the Metropolitan Police Service (MPS) continue to piece together exactly what occurred," police said in a statement, adding that searches of "a number of addresses" in Barking are ongoing.
11:49 In separate statements, the United Arab Emirates, Qatar, Bahrain, Oman and Kuwait condemn the attacks in London and voiced their support for the British government. The Turkish Foreign Ministry has also expressed the country's "deep sadness" and stressed Turkey's readiness to help the UK in the fight against extremism.
11:13 British broadcaster Sky News says a building raided by armed police on Sunday in the Barking area of east London is at the address of one of the London Bridge attackers. Sky also reported that four men and one woman had been arrested during the raid.
10:45 Pope Francis offers prayers for the victims of the London attacks during a traditional Sunday blessing following a mass that marked the Pentecost holiday.
10:38 European Commission President Jean-Claude Juncker says that the attacks "will not undermine our resilience, our compassion or our democracies," going on to say that the "European Union, its member states and its allies around the world will stand with (the people of London) in solidarity." He adds: "Together we will continue to uphold the values that make us peaceful, democratic, open and tolerant societies."
10:15 Spain's Foreign Ministry says one Spanish man was wounded in the attacks and was being treated in hospital. A spokesman said the wounds were not serious.
10:13 British Home Secretary Amber Rudd tells ITV television that the government is confident that those behind the attack were "radical Islamist terrorists." She said that Britain's terror threat level, currently at "severe," had not been raised to its highest level of "critical" because authorities believed all the perpetrators directly involved were dead.
10:09 Iran's Foreign Ministry spokesman, Bahram Ghasemi, condemns the "terrorist attacks" in London and expresses sympathy for the families of the victims. He calls the growing number of extremist attacks "an alarming signal for the global community," and condemns terrorism in "all shapes and aspects regardless of purpose and motive."
09:55 French Foreign Minister Jean-Yves Le Drian now says four French citizens were among those injured in Saturday's attacks, with one person "particularly affected."
09:53 British broadcaster Sky News says a police operation is underway in the Barking area of east London.
09:42 Prime Minister Theresa May says "enough is enough," adding that people must be allowed to live freely. She also says that Thursday's general election must go ahead. Her final words were: "United we will take on and defeat our enemies."
09:41 May calls for more social unity in the fight against terrorism.
09:40 According to May, there must be more control of the internet to take away terrorists' "safe spaces" to spread their ideology.
09:38 May says terrorists are united by a "single evil ideology" that perverts Islam and depicts it as incompatible with Western values.
09:37 Security forces and intelligence agencies have disrupted five planned terror attacks since the Westminster attack in March, May says.
09:35 She praises the quick response of security forces.
09:34 Prime Minister Theresa May emerges from 10 Downing Street to address reporters following the meeting of COBRA, the government's crisis response committee.
09:08 The leader of the anti-EU UK Independence Party, Paul Nuttall, says his party will not join others in suspending election campaigning in the wake of the London Bridge attacks.
09:01 British Prime Minister Theresa May says on Twitter that she will make a statement following a meeting of the government's crisis response committee, COBRA.
08:31 Metropolitan Police Commissioner Cressida Dick says the death toll from the attack has now risen to seven. She says that although the police believe the incident was under control and that no suspects were still at large after three assailants were shot dead, there was a large police cordon still in place at the scene. She called on Londoners to remain vigilant, but to allow police and security agencies to get on with their work. She also said she did not know the identity of the suspects.
08:02 Russian President Vladimir Putin has "condemned" the London attacks and sent condolences, according to the Kremlin.
08:02 The opposition Labour Party also confirms that it will suspend its national election campaigning on Sunday after the London attacks.
07:25 A spokesman for the Scottish National Party said it would also call off national campaigning on Sunday following Saturday's attacks.
07:22 Australian Prime Minister Malcolm Turnbull says two Australian citizens were caught up in the attack, with one confirmed to be in hospital.
06:16 London Mayor Sadiq Khan says there will be an increased police presence across London in the coming days. He called on people to go to vote on Thursday without being intimidated by terrorism. "One of the things these terrorists hate is voting; they hate democracy."
06:13 Sadiq Khan says there is no justification for the actions of these terrorists. He praised emergency services for their "brilliance," calling them the best security services in the world. He also asked for people to remain calm and vigilant.
06:10 In a statement, French President Emanuel Macron's office says that at least two French citizens have been injured, one seriously.
06:03 A spokesman for Prime Minister Theresa May confirms that the ruling Conservative Party will be suspending national campaigning on Sunday for the upcoming election.
05:57 The political editor of broadcaster ITV, Robert Peston, tweets that national campaigning for Thursday's national election is being suspended on Sunday, but that local campaigning is to continue.
05:45 The spokesman for German Chancellor Angela Merkel, Steffen Seibert, tweets: "Our thoughts are with the people in London. We stand together against terror." His tweet also included a statement from Merkel, in which she speaks of her "grief and dismay" at the attacks." She said her thoughts were with the victims of the attacks and their families. And she added that Germany "stood firmly and resolutely at Great Britain's side in the fight against every form of terrorism."
05:33 Indian Prime Minister Narendra Modi, returning home from a trip to Europe, condemns the attacks in London, saying his thoughts were with the families of the deceased and offering prayers for the injured.
05:19 The London Ambulance Service raises the number of patients taken to hospitals to 48.
04:22 Canadian Prime Minister Justin Trudeau says that Canadians "stand united" with London after the attacks. And in a tweet, he spoke of "awful news."
03:08 London Ambulance Service says more than 30 people have been taken to five hospitals across London for treatment.
02:50 London police say six people have died in the attacks on London Bridge and Borough Market. Assistant Commissioner Mark Rowley told reporters officers shot and killed three male attackers, and that no more suspects were believed to be at large. He added, however, that an investigation was ongoing and more work needed to be done.
Rowley also provided more details about how the events of the night unfolded. Police believe the militants drove a white van into pedestrians on London Bridge before abandoning the car at Borough Market and stabbing a number of people in restaurants and bars.
"Armed response officers then responded very quickly and bravely and confronted the three male suspects who were shot and killed on Borough Market," Rowley said, adding that the suspects were wearing fake explosive vests. He says additional police officers would be deployed to the British capital in the coming days.
02:45 US President Donald Trump called Prime Minister Theresa May to offer his condolences.
01:53 DW's UK correspondent Birgit Maass reports Londoners have been offering help to those caught up in the attacks, as was the case in Manchester two weeks ago.
01:40 London Ambulance Service says it has taken at least 20 people to six hospitals across the city, adding that a number of people were treated at the scene for less serious injuries.
01:27 Photographer Gabriele Sciotto posted a photo on social media showing one of the alleged suspects lying on the ground with canisters strapped to his body after he was shot by police in Borough Market. Another man is seen lying on the ground a short distance away.
01:17 Australia's foreign minister described the incidents as "shocking."
"We stand ready to support the British government as it responds to these attacks and our thoughts are with those injured and their families," Foreign Minister Julie Bishop said.
01:15 French President Emmanuel Macron says France stands "more than ever at Britain's side...My thoughts go out to the victims and their loved ones."
01:10 Three major London hospitals say they have gone into lockdown after the attacks the near London Bridge.
"Due to the ongoing incident in central London, Guy's, St Thomas' & @EvelinaLondon are on lockdown to keep patients, relatives and staff safe," the authority that runs the hospitals said on Twitter.
0:55 Ariana Grande paid tribute to the victims of the London attacks. Twenty-two people were killed in a suicide bombing at the popstar's Manchester concert last month.
0:53 The US State Department says it "condemns the cowardly attacks targeting innocent civilians in London."
Armed police shot dead the three attackers within eight minutes of receiving the first emergency call
0:39 London's Mayor, Sadiq Khan, has described the violence as a "deliberate and cowardly attack on innocent Londoners."
"I condemn it in the strongest possible terms. There is no justification whatsoever for such barbaric acts," he said.
0:23 An eyewitness told Reuters news agency that at least six people were seen on the ground after a white van mounted the curb and ploughed into pedestrians on London Bridge. "It looked like he was aiming for groups of people. I froze because I didn't know what to do," Mark Roberts, 53, said.
"I could see six people on the floor not moving. And there were groups of people helping those people on the ground...After that I heard what sounded like gunfire from Borough Market."
Londoners wrapped in foil blankets leave the London Bridge area after a van ploughed into pedestrians
00:09 Police are urging the public to use restraint in sharing pictures and videos of the incidents.
23:56 UK police have confirmed that the incidents at London Bridge and Borough Market are terrorist-related, but a separate stabbing in the Vauxhall area was not connected.
23:45 Prime Minister Theresa May says the London incident is being treated as a "potential act of terrorism."
"This is a fast moving investigation," May said in a statement. "I want to express my huge gratitude to the police and emergency services who are on the scene. Our thoughts are with those who are caught up in these dreadful events."
23:37 US President Donald Trump offered his support to Britain. He also called for his travel ban stopping people from several Muslim countries entering the US to be implemented.
23:35 Opposition leader Jeremy Corbyn calls the incidents "brutal and shocking."
23:20 Downing Street says Prime Minister Theresa May will chair a meeting of the government's emergency response committee, COBRA, on Sunday. A spokesman says she is receiving regular briefings on the situation.
22:40 The British transport police say there are reports of "multiple" casualties. Nick Brandon in the force's control room says the seriousness of the injuries is not yet known.
22:30 The Metropolitan Police posted on Twitter that officers responded to a second incident in Borough Market where there were reports that people had been stabbed. Police said shots had been fired. Authorities are also responding to a third incident in the Vauxhall area.
21:08 Armed police in London rushed to London Bridge following reports that a white van had driven onto the sidewalk and struck multiple pedestrians. The London Bridge station and surrounding area was closed at the request of police.
tj/jw (AP, Reuters, AFP)