In summary:
- 40 people hurt - including some with “catastrophic” injuries
- Identity of lone terrorist yet to be confirmed by police
- Woman Pulled Alive From Thames After Falling During Attack
- MP Former Soldier Hailed As Hero For CPR On Fallen Officer
- Shocked Eyewitnesses Describe Horror Scene At Westminster
- Theresa May Bundled Out Of Voting Lobby By Plain Clothes Police
Terror struck at the heart of British democracy on Wednesday after four people were killed - including the attacker and a police officer - at the Houses of Parliament.
Three others, one believed to be a female pedestrian, were killed during a car rampage on Westminster Bridge which also left at least 40 people hurt - including some with “catastrophic” injuries.
Scotland Yard tonight confirmed the police officer killed was PC Keith Palmer, 48, who was unarmed. He was married with children.
Police were originally believed to be investigating whether a second attacker was involved, but have since said they are not looking for another suspect.
Police were initially alerted to the attack after a vehicle mounted the pavement and began mowing down pedestrians on Westminster Bridge at around 2:40pm.
Moments later a knife-wielding attacker, believed to the driver, stabbed a police officer and was shot on the grounds of Parliament.
The Parliament complex remains on lockdown. Deputy Commons Speaker Lindsay Hoyle told MPs they would be the last parliamentary staff to be evacuated, and would be moved out in groups of 20.
Theresa May was whisked away to Downing Street, where she chaired a meeting of the Government’s emergency Cobra committee and later gave a statement.
Just before 9pm, she spoke from outside Number 10 to describe the attack as “sick” and “depraved”.
“These streets of Westminster are ingrained with a spirit of freedom that echoes in the furthest corners of the world,” May said.
The PM also confirmed Parliament would sit as normal on Thursday.
Witness Rick Longley told the Press Association that earlier he had seen a man stab a policeman outside 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.”
French Prime Minister Bernard Cazeneuve confirmed several schoolchildren from the country were among those injured in the attack.
An eye-witness told The Huffington Post UK that the suspect appeared to attack a police officer who fell to the ground.
Shots were then fired and the assailant fell to the ground as he tried to get out of New Palace Yard, the witness said.
Conservative MP Tobias Ellwood attempted to save the policeman’s life by giving him mouth-to-mouth.
Elwood - a former soldier and foreign minister - remained with the injured officer until an air ambulance arrived, and was later seen with bloodied hands.
Met Commander BJ Harrington confirmed to reporters this evening that there were “a number of casualties” in the Westminster attack, “including police officers”.
Three police officers are believed to have been hit by a grey 4x4 Hyundai being driven by the attacker across Westminster Bridge. The car was reportedly registered to an address in Chelmsford, Essex.
Reporters at the scene said they could see at least one body covered with a blanket while another person was receiving CPR before being put in an ambulance.
London Ambulance Service confirmed at least 10 patients were been treated on Westminster Bridge and a number of hospitals are on alert.
Sky’s Tamara Cohen added that the Prime Minister was “bundled out [of Parliament] by [a] plain clothes policeman” when the news broke.
May later chaired an emergency Cobra meeting from Downing Street.
Cobra - or Cabinet Office Briefing Room A - so named because of the room its members meet in, coordinates the high-level response to serious incidents. It brings together government ministers with senior officials of the emergency services and security and intelligence agencies.
A separate eyewitness who was in Parliament when the attack happened told HuffPost UK: “I heard what sounded like an explosion and raised voices outside Parliament, and so I rushed to the window.
“I saw people running past the entrance to the New Palace Yard entrance to Parliament, and then at least one person try to run into the Yard itself. A police officer chased this person and wrestled them to ground.
“Shots were then fired, but I can’t remember how many and I didn’t see who fired them.
“I ran down the stairs from my office overlooking the Yard to get more information, but the police prevented us from leaving the stairwell.
“When I returned to my office, I could see two people lying on the ground outside Westminster Hall, but neither of these were the person I saw wrestled down by the police officer minutes earlier.”
A junior doctor at nearby St Thomas’ Hospital, Colleen Anderson, described a scene of carnage as people fled the attacker.
She said: “There were people across the bridge. There were some with minor injuries, some catastrophic. Some had injuries they could walk away from or who have life-changing injuries.”
Other political reporters based in the area shared their version of events:
The House of Commons was briefly suspended, but after a statement from its Leader David Lidington, it was adjourned.
Lidington told MPs in the chamber: “What I am able to say to the House is that there has been a serious incident within the estate.
“It seems that a police officer has been stabbed that the alleged assailant was shot by armed police. An air ambulance is currently attending the scene to remove the casualties.
He continued: “It would be wrong of me here to go into further details until we have confirmation from police and from the house security authorities about what is going on.”
Jeremy Corbyn said afterwards that his “thoughts are with the victims of this horrific attack, their families and friends”.
He added: “The police and security staff have taken swift action to ensure the safety of the public, MPs and staff, and we are grateful to them.”
Mayor of London Sadiq Khan also released a statement, saying:
“There has been a serious incident near to Parliament Square this afternoon which is being treated as a terrorist attack until the police know otherwise.
“I have spoken to the Acting Commissioner. The Metropolitan Police Service is dealing with the incident and an urgent investigation is underway. My thoughts are with those affected and their families.
“I would like to express any thanks to the police and emergency services who work so hard to keep us safe and show tremendous bravery in exceptionally difficult circumstances.”
The incident happened on the one year anniversary of the Brussels bombings, which killed 32 people and wounded more than 300.
In Scotland, MSPs have delayed a vote on a possible second independence referendum in light of the attack in Westminster. The Scottish Parliament and Welsh Assembly were both suspended for the day.
A BBC journalist also tweeted:
Police have opened a dedicated phone line for victims injured in the attack and concerned friends and family on: 0800 056 0944 or 0207 158 0010