2:55 p.m. (Greenwich Mean Time Zone)
A session of Britain's House of Commons was suspended as witnesses reported hearing sounds like gunfire nearby.
The leader of Britain's House of Commons said a man was shot by police at Parliament. David Lidington also said there were "reports of further violent incidents in the vicinity." London police said officers had been called to a firearms incident on Westminster Bridge, near the parliament.
The leader of Britain's House of Commons said a man attacked a police officer at Parliament and has been shot by police.
A European security official said there was increased chatter on jihadi networks Tuesday following the UK's adoption of an electronics ban aboard flights from certain mostly Muslim countries. At this time, the official said that there was no information that the incident was terror-related.
London police said they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." The Metropolitan Police says in a statement that the incident is ongoing. It is urging people to stay away from the area.
The former Polish foreign minister Radek Sikorski posted a video on Twitter that seems to show people lying injured in the road on Westminster Bridge.
British lawmaker Grant Shapps said on Twitter that he was walking through the cloisters of the House of Commons to vote when he heard four gunshots. Police told lawmakers to get down on the ground and crawl to cover.
The White House says U.S. President Donald Trump has been briefed on a gun and knife incident at Britain's Parliament in London. Trump himself said during a brief appearance Wednesday before reporters at the White House that he was just getting the news. He called it "big news."
Witness Rick Longley told the Press Association that he saw a man stab a policeman outside Britain's Parliament. "We were just walking up to the station and there was a loud bang and a guy, someone, crashed a car and took some pedestrians out," he said.
"They were just laying there and then the whole crowd just surged around the corner by the gates just opposite Big Ben. A guy came past my right shoulder with a big knife and just started plunging it into the policeman. "I have never seen anything like that. I just can't believe what I just saw."
The U.S. State Department said it is closely monitoring the incident outside London's Parliament and urged Americans in London to avoid the area.
Poland's former foreign minister, Radek Sikorski, said he was in a taxi leaving Westminster and was checking his email when he heard something like a car crash, "something like a car hitting metal sheet. I look up and I see that a person is lying on the pavement. I started my camera and I saw more people lying on the street and on the pavement," Sikorski said on Poland's TVN24.
A doctor said a woman has died and about a dozen people are hurt, some with "catastrophic" injuries, after a vehicle apparently hit pedestrians on Westminster Bridge, near Parliament.
A senior police commander said the attack at London's Parliament has been declared a terrorist incident and "a full counterterrorism investigation is underway."
The London Ambulance Service said it has treated at least 10 injured people on Westminster Bridge after a vehicle hit pedestrians.
Britain's Prime Minister Theresa May will chair a meeting of the government emergency committee to discuss the response to the terror incident in London.
British port officials said they pulled a woman from the Thames River following the incident on Westminster Bridge. The Port of London Authority says a female member of the public was recovered from the river, injured but alive.
Three students on a school trip from Saint-Joseph high school in the Brittany town of Concarneau were among the injured, according to the French foreign ministry.
Russian Foreign Ministry spokeswoman Maria Zakharova expressed sympathy to those injured and condolences to the relatives of those who died in the incident at Britain's parliament, and has underlined the need for global cooperation in the fight against terrorism.
French President Francois Hollande and German Chancellor Angela Merkel both expressed their support and solidarity with Britain after the attacks at the British Parliament in London. "We are all concerned with terrorism," Hollande told reporters Wednesday during a visit in Villepinte, outside Paris. "France, which has been struck so hard lately, knows what the British people are suffering today."
The head of counterterrorism at London's Metropolitan Police, said four people have died in the terror incident in London, including an attacker and a police officer. Mark Rowley says some 20 people have been wounded and Parliament was locked down. A search is underway to make certain no other attackers are in the area - though police believe there was only one attacker.
The Italian interior ministry said the nation's top security and intelligence officials will huddle in Rome on Thursday for "an evaluation of the terrorist threat" after the attacks in London.
The White House is condemning the attacks in London involving a car rampage and knife attack. President Donald Trump is said to be monitoring developments. Spokesman Sean Spicer said Wednesday Trump spoke with British Prime Minister Theresa May and said that the White House applauds "the quick response of British police and first responders" and condemns the attacks.
One British lawmaker was hailed by some as a hero in Wednesday's attack on the British Parliament. Conservative parliamentarian and Foreign Office minister Tobias Ellwood, whose brother was killed in the Bali terror attack in 2002, performed mouth-to-mouth resuscitation on the police officer who was stabbed and later died. About 10 yards away was the attacker who was shot dead by police after scaling the security wall toward Parliament's grounds.
Spanish Prime Minister Mariano Rajoy condemned the deadly attack in London's Westminster on Wednesday and offered condolences to the British people in a telegram sent to his British counterpart Theresa May.
"An execrable terrorist act like the one that took place today is a reminder that we face complex challenges for the security of our societies," said Rajoy in a transcript of the telegram distributed by Moncloa, the prime minister's palace.
The Associated Press contributed to this report.