An alleged assailant has been shot after stabbing a policeman outside the British parliament. There were also reports of a car plowing into several people on Westminster Bridge.
What we know so far:
All updates in Universal Coordinated Time (UTC).
21:00 Read more about reactions on the ground from DW correspondent Abigail Frymann Rouche.
20:04 Angus Mercer, a consultant located near Westminster, tweeted a shot of the normally bustling embankment.
18:43 Interior Minister Amber Rudd said the British people's security was the government's top priority. "The British people will be united in working together to defeat those who would harm our shared values: values of democracy, tolerance and the rule of law."
18:23 The UK Parliament confirmed on Twitter that both chambers will sit tomorrow at their normal times.
18:15 US President Donald Trump has spoken with British Prime Minister Theresa May about the attack at Westminster. Trump reportedly offered the support of the US government.
18:05 Police confirmed that four people have died and at least 20 people have been injured. One of those who died was the attacker.
18:04 German Chancellor Angela Merkel has released a statement regarding the incident. "Although the background to these acts are not yet clear, I reaffirm that Germany and its citizens stand firmly and resolutely alongside Britons in the struggle against all forms of terrorism," Merkel said.
17:40 One of the people confirmed killed was a police officer, the BBC reported. The officer died at the scene.
17:25 Several French high school students were among those injured in the attack, according to French officials.
17:22 DW London correspondent Abigail Frymann Rouch said the scene near Westminster was calm "but for roar of helicopters."
17:20 Officials said they have pulled a woman, injured but alive, from the Thames River.
17:15 DW's Sofia Diogo Mateus reports that Facebook has activated its safety check feature.
16:53 British Prime Minister Theresa May will chair an emergency Cobra meeting on Wednesday to discuss the incident, UK media report.
16:52 The London Ambulance Service said it had treated at least 10 people on Westminster Bridge.
16:44 Scotland Yard Commander BJ Harrington confirmed during a press conference that police are treating the actions as "a terrorist incident" but that they "remain open-minded to the motive," calling it an "ongoing investigation." He said that there were "a number of casualties, including police officers," but couldn't confirm the number or natures of the injuries. He said he was "not prepared to speculate" and appealed to the public for more information.
16:39 Sky News reporting that two people have now been confirmed dead.
16:34 Angus Mercer, a consultant located near Westminster, described the scene to DW via phone. "Traffic is backed up, there are diverted traffic signs and regular police sirens. People are pretty on edge, and it is a scary time," Mercer said. "I think people on my floor of the building are largely staying inside unless they have a pressing need to do anything else. It is late in the working day so people are trying to crack on with work as normal." He said there were also helicopters flying over downtown London.
16:17 At least person confirmed dead and others have "catastrophic" injuries, according to UK news agency Press Association.
16:12 The official Twitter account of the London Eye, the giant ferris wheel located across the Thames, said on Twitter it was "holding all of our guests within our attractions as per tried and tested security procedures." Here's a map giving a better look at the exact location where the incidents occurred.
16:00 The Scottish parliament has suspended a debate being held today over a mandate for a new independence referendum. Scotland's Minister for Transport and the Islands confirmed this on Twitter.
15:59 French presidential candidate Francois Fillon tweeted his condolences. "I assure the British people, once again the target of barbarism, of my full support and solidarity."
15:58 Scottish First Minister Nicola Sturgeon tweeted her condolences.
15:49 There are reports of heavily bleeding individuals.
15:44 US President Donald Trump has been briefed of the incident. "Just getting an update on London," Trump said as he entered a meeting in the White House's Roosevelt Room. "Big news." White House spokesman Sean Spicer said they were continuing to monitor the situation and update the president.
15:42 Metropolitan Police have issued a public statement telling the public to avoid downtown areas.
15:41 David Lidington, leader of the House of Commons, told the BBC that he had heard four shots before he heard police yell "Get down! Get down!"
15:40 Traffic in the area of Parliament had been closed.
15:38 The BBC reported that the incident with the car on Westminster Bridge occured at 20 minutes before 3pm local time (14:40)
15:36 The Associated Press news agency reported that an anonymous European security official said there had been increased "chatter" on jihadi networks after the UK electronics ban.
15:32 DW correspondent Gerhard Elfers described a "confused picture" on the ground in London during a live interview.
15:32 Metropolitan Police tweeted that they are treating this "as a terrorist incident."
15:31 Prime Minister Theresa May has been confirmed safe, though it is not clear if she has been evacuated.
15:30 "We are aware of reports of an incident at Westminster," the Metropolitan Police said, according to German news agency DPA. "Officers - including firearms officers are on the scene and dealing with the incident."
15:26 German government spokesman Steffen Seibert tweeted his condolences in English to Britain.
15:16 The leader of the House of Commons said a man was shot by police after attacking a police officer at Parliament.
15:09 A Labour MP tweeted that he was locked in the Commons Chamber.
14:51 London police confirmed that they had been called to a "firearms incident" on Westminster Bridge and said they will "put more information out as soon as we can."
14:49 Parliament was suspended on Wednesday following reports of gunfire and at least a dozen injuries around Westminster Bridge.
14:47 An observer at the scene tweeted the following video showing images from the scene.
14:47 Another observer at the scene said he saw a car mow down "at least 5 people" on Westminster Bridge. The video, which was taken by Radoslaw Sikorski, the former Polish foreign minister, purportedly shows the scene on the bridge.
14:42 Reporters inside the parliament were told not to leave the building as reports circulated of a stabbing incident in addition to a shooting. However, it was still unclear to those at the scene what had transpired.
Charlie Cooper, a political correspondent for Politico, said he saw police shoot a man outside the parliament building and that there were at least two casualties.