Five people, including a police officer, were killed in a suspected terror attack outside the British Parliament by an attacker who was shot dead by police, Britain's top anti-terror officer said on Wednesday.

Parliament was locked down on Wednesday after the attacker stabbed an officer and was then shot by police. Witnesses said a vehicle struck several people on the nearby Westminster Bridge. Police said they were treating the attack as a “terrorist incident until we know otherwise”.

A woman assist an injured person after an incident on Westminster Bridge in London on Wednesday. | Photo Credit: Reuters

Updates:

12.42 p.m.: China says one of its citizens was among the 40 people injured in the attack outside Britain’s Parliament, and is urging Chinese nationals in the U.K. to avoid crowded areas or travelling alone at night. The Chinese Embassy in London said it was in touch with the family of the Chinese citizen injured in the attack. Chinese President Xi Jinping condemned the attack, sent condolences to Queen Elizabeth II and to the families of those killed. He also wished speedy recovery of the injured.

12.20 p.m.: Police made several arrests in a raid on a house in Birmimgham as part of the investigation into the attack, Sky News television channel quoted unidentified sources as saying.

8.00 a.m.: World leaders unanimously condemned the attack, with many saying they stand with Britain.

7.40 a.m.: Prime Mister Narendra Modi condemned the attack, saying, "India stands with the U.K. in the fight against terrorism."

Deeply saddened by the terror attack in London. Our thoughts and prayers are with the victims and their families. — Narendra Modi (@narendramodi) March 23, 2017 At this difficult moment, India stands with UK in the fight against terrorism. @theresa_may @Number10Gov — Narendra Modi (@narendramodi) March 23, 2017

7.15 a.m.: U.K. Prime Minister Theresa May termed the terror strike a “sick and depraved” attack on democratic values, which was “doomed to failure”. After chairing an emergency Cobra meeting at Downing Street, she confirmed that the attack was carried out by a single attacker who drove his vehicle into pedestrians walking across the Westminster Bridge, killing two people and injuring many more, including three police officers.

7.00 a.m.: South Korea’s Foreign Ministry says five South Koreans in their 50s and 60s were among the 40 people injured in London in the attack. Five were hurt when they were caught in a stampede of people trying to escape the attack. Four of the South Koreans suffered broken bones and other injuries and a woman in her late 60s needed an operation to treat a head injury, it said.

5: 00 a.m.: U.K's Foreign Minister Boris Johnson tweets about the incident.

Heartbreaking. This is not the first attack on London or our Parliament - and won't be the last - but our values will prevail. — Boris Johnson (@BorisJohnson) March 22, 2017

4.45 a.m.: Death toll in the attack is five, say police. Counter-terrorism chief Mark Rowley said one policeman, three civilians and the attacker died. The assailant has not been identified. Mr. Rowley said police think they know the identity of the man but would not reveal details. He said Islamic extremism is suspected in the attack.

4.30 a.m.: Police say they might know the identity of the attacker; "Islamist-related terrorism is our assumption," they say.

4.15 a.m.: Buckingham Palace officials say Queen Elizabeth II will postpone plans to open the new Scotland Yard headquarters.

The palace said on Wednesday night that the queen’s visit, which was set for Thursday, would be postponed. The change is due to security concerns raised by the Wednesday terror attack. It is also expected that police will be involved with a major investigation that will occupy many officers. The queen was to have been joined by her husband Prince Philip at the official opening of the new building.

4. 00 a.m.: “India strongly condemns Westminster terrorist incident & condoles loss of life. No place in democracies & civilised societies for terrorism (sic),” spokesperson, Ministry of External Affairs, Gopal Baglay tweeted.

3. 26 a.m.: Five South Korean tourists were injured in the terror attack, says foreign ministry in Seoul.

The tourists — four women and a man in their 50s or 60s — were knocked to the ground by people trying to flee as an assailant mowed down pedestrians in a car, the ministry said.

While four of them suffered relatively light injuries including a fracture, one — a woman in her late 60s — suffered a head injury and was going through surgery, it said. They were being treated in two local hospitals, it added.

An injured person being treated by emergency services near Westminster Bridge and the Houses of Parliament on March 22, 2017 in London, England. | Photo Credit: Carl Court/Getty Images

2. 42 a.m.: Prime Minister Theresa May has condemned the “sick and depraved terrorist attack” in London and says the targeting Parliament was no accident. In a late-night statement outside her Downing Street office on Wednesday, May said the nation will not give in to terror and those who targeted the seat of power in Britain.

She insisted that “tomorrow morning Parliament will meet as normal,” and urged the country to move on and behave as normal on Thursday.

May says “we will all move forward together, never giving in to terror and never allowing the voices of hate and evil to drive us apart.”

The prime minister confirmed that four people died in the attack and praised the security services who ran toward danger.

2.00 a.m. German Chancellor Angela Merkel said on Wednesday that Germany stood by Britain “firmly and resolutely”, following the terror attack near the British parliament.

1.00 a.m.: Sushma Swaraj tweets, "Indian High Commission is there to help all Indian nationals in London. Tel. no.s : 020 8629 5950 & 020 7632 3035 (London) .

12.40 a.m.: My heartfelt sympathies to those families who have lost loved ones and to all those injured in the attack on Westminster, tweets former British Prime Minister Gordon Brown

12. 02 a.m.: Thoughts with those killed and injured in Westminster attack: Official statement from 10, Downing Street. The Prime Minister Theresa May is yet to address the people. She is expected to chair an emergency meeting of the government's COBRA emergencies committee later in the day.

11.30 p.m.: Tourists were stuck in mid-air on the popular London Eye attraction for around an hour. Visitors on the London Eye, a 135 metre (443 foot) high big wheel, were later evacuated after the attack, in which a police officer was stabbed and the suspected assailant shot.

The London Eye has a clear view over the area. "At present we are holding all of our guests within our attractions as per tried and tested security procedures," the attraction said on its Twitter page. The account later tweeted that the passengers "are now disembarking". The London Eye is made up of 32 white pods, each of which can carry 25 people.

10. 00 p.m.: One woman killed and others suffered "catastrophic" injuries, local media reported citing a junior doctor. Eyewitnesses told British media the attacker mowed down pedestrians on Westminster Bridge before crashing his car into railings outside the Houses of Parliament then running out with a knife, stabbing a police officer and then being shot.

9. 30 p.m.: 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.”

Lawmaker Adam Holloway told the AP he saw people running and immediately ran into his offices in Parliament to be with his staff. “A lot of us are locked in with our staff at the moment,” he said. - AP

9.16 p.m.: 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.

“Police response instant. Heard commotion, looked round. Police weapons drawn, 4 shots, police ordered us to hit ground & get back, get back,” he said. - AP

9.15 p.m.: The former Polish Foreign Minister Radoslaw Sikorski posted a video on Twitter that seems to show people lying injured in the road on Westminster Bridge.

Mr. Sikorski, a senior fellow at the Harvard Centre for European Studies, says he saw at least five people lying on the ground after being “mown down” by a car.

Mr. Sikorski told the BBC he “heard what I thought what I thought was just a collision and then I looked through the window of the taxi and someone down, obviously in great distress.

“Then I saw a second person down, and I started filming, then I saw three more people down, one of them bleeding profusely.” - AP

A woman assist an injured person after an incident on Westminster Bridge in London on Wednesday. | Photo Credit: Reuters

9 p.m.: Prime Minister Theresa May is safe after an assailant was shot outside Parliament by police on Wednesday, a spokesman of her office said.

The spokesman declined to say where Ms. May was when the attack took place, reports AP

The Jagaur car of British Prime Minister Theresa May is driven away from the Houses of Parliament in London on Wednesday. | Photo Credit: AFP

8.30 p.m.: At least a dozen people have been injured on Westminster Bridge after large bangs were heard outside Parliament, a Reuters photographer says.

8.25 p.m.: Two people shot outside Parliament, building in lockdown, reports Reuters; Armed police seen running to exit from Parliament; Parliament suspends work in House of Commons, says Deputy Speaker

8.15 p.m.: Loud bangs heard outside U.K. Parliament, Reuters reports.