An MP carrying out his normal duties, attacked while meeting constituents, ITV News UK Editor Paul Brand reports
Counter-terrorist officers have begun investigating the death of Conservative MP Sir David Amess, who died after being stabbed several times while holding a constituency surgery in Leigh.
The Metropolitan Police have confirmed his death is being treated as a terrorist incident and said there was “a potential motivation linked to Islamist extremism”.
The Southend West MP was holding the surgery at the Belfairs Methodist Church, in Eastwood Road North, when a man ran into the church, according to the Southend Echo.
The newspaper reported the 69-year-old was then stabbed "several times" - the incident took place around midday.
What have the police said about the incident?
He was "treated by emergency services but, sadly, died at the scene", police added.
Essex Police said a 25 year-old man was arrested on suspicion of murder and a knife was recovered from the scene - the force said it was not looking for anyone else in connection with the attack.
At a press conference, Essex Police Chief Constable Ben-Julian Harrington said an investigation into the killing "is in its very early stages and is being led by officers from the specialist counter-terrorism command".
What has really changed since Jo Cox? Paul Brand reports
While counter-terrorism officers are investigating the death, Chief Con Harrington added: “It will be for investigators to determine whether or not this is a terrorist incident, but as always they will keep an open mind."
The force had initially said they had arrested a foreign-born man, but they've since back-tracked and confirmed the suspect is British.
What we know so far:
The Southend West MP was fatally injured at Belfairs Methodist Church in Leigh-on-Sea in Essex at midday on Friday and died at the scene.
Essex Police said the response of the emergency services to the incident was immediate and officers arrived at the scene within minutes.
A 25-year-old man was arrested immediately at the scene on suspicion of murder and remains in custody.
Metropolitan Police declared the incident an act of terrorism, with early investigations revealing “a potential motivation linked to Islamist extremism”.
Police said a knife was recovered.
Detectives are not looking for any other suspects, though the Met said officers were carrying out searches at two addresses in the London area as part of their investigation.
Why are counter-terrorism involved?
Sir David had been a Member of Parliament since 1983, starting by representing Basildon before moving to Southend West in 1997. Tributes have poured in from across the political divide.
Prime Minister Boris Johnson said all our hearts are filled with "shock" and "sadness", as he reacted to his colleague's death.
He added: "The reason people are so shocked and sad is above all he was one of the kindest, nicest, most gentle people in politics.
"He also had an outstanding record of passing laws to help the most vulnerable."
What is currently known about the attacker? Essex police give a statement following Sir David's death
The prime minister said now is the time "let the police get on with their investigation", adding it is too soon to be considering additional measures to improve the safety of MPs.
"All those issues will be considered in the proper time," he said, but Home Secretary Priti Patel said it was right that questions are being "asked about the safety of our country's elected representatives".
She said she would provide "updates in due course" on what the government response will be.
Helicopter footage from Friday shows the scene on the ground:
Aerial footage from Friday afternoon showed an air ambulance stationed near to the scene as well as multiple ambulance crews outside the Belfairs Methodist Church.
Armed police were also on site, with a large cordon in place around the church and down the street.
Members of the public had gathered at the scene, with one man comforting a woman outside.
A large cordon was extended down Eastwood Road on Friday, closing multiple side streets off.
The Union flags above Downing Street were lowered to half mast in a mark of respect following Sir David's death.
It's the latest in a series of violent attacks on MPs
The attack is the latest in a string of violent attacks on MPs, which includes the 2016 murder of Labour MP Jo Cox.
She was killed while on her way to hold a surgery with constituents in Batley and Spen.
In May 2010, East Ham MP Stephen Timms was stabbed twice in the abdomen by Roshonara Choudhry, an Islamic extremist who claimed she had wanted "to get revenge for the people of Iraq".
Nigel Jones, then MP for Cheltenham, was severely injured in January 2000 when he was attacked in his offices by a man with a sword.
Andrew Pennington, a Gloucestershire county councillor, was killed in the same attack while trying to defend the then-MP.
And in 1990 Conservative MP Ian Gow was assassinated by the Provisional Irish Republican Army.
Home secretary Priti Patel said all police forces must now review security arrangements for MPs "with immediate effect".
The request came after she chaired a meeting of the Police, Security and Intelligence Agencies and consulted Speaker of the House of Commons Sir Lindsay Hoyle
Sir Lindsay said a discussion should follow Sir David's death on whether the security of MPs needs to be improved.
He said: "This is an incident that will send shockwaves across the parliamentary community and the whole country.
"In the coming days we will need to discuss and examine MPs’ security and any measures to be taken, but for now, our thoughts and prayers are with David’s family, friends and colleagues."
The sister of Ms Cox, Kim Leadbeater, who is now an MP for Ms Cox's former constituency, said she felt "frightened" following the attack on the Tory MP.
She said: "I find myself now working as a politician and trying to do good things for people and it's really important you get good people in public life, but this is the risk we are all taking and so many MPs will be scared by this.
"My partner came home and he said he didn't want me to do it any more because the next time that phone goes, it could be a different conversation."
Paula Sherriff, a former Labour MP who was close to Sir David, said the police need to take threats to MPs much more seriously.
"Towards the end of my tenure as an MP, the amount of abuse we were receiving...death threats became a really common occurrence," said Ms Sherriff, who served from 2015 to 2019.
"We'd sit in the tea room at Parliament and talk about death threats we'd received at the weekend like it was normal conversation,"
Tributes pour in for Sir David
Tributes have been paid to the long-standing MP, with former prime minister David Cameron sending "thoughts and prayers" to Sir David and his family following the "very alarming and worrying news".
The Jo Cox Foundation, set up in her name following her murder tweeted, saying it is "horrified to hear the news of the attack".
Ms Cox's widower Brendan Cox described the attack as "as cowardly as it gets".
He said the incident "brings everything back", adding: "The pain, the loss, but also how much love the public gave us following the loss of Jo. I hope we can do the same for David now."
Meanwhile, the Duke and Duchess of Cambridge tweeted: "We are shocked and saddened by the murder of Sir David Amess, who dedicated 40 years of his life to serving his community."
"Our thoughts and prayers are with his family, friends and colleagues."
East Ham MP Mr Timms, who was stabbed at a constituency surgery in 2010, wrote on Twitter before Sir David's death was confirmed: "Appalled to hear of the attack on @amessd--southend today. I know him well and am thinking of him with very best wishes as we await further news."
Former PM Theresa May also paid her condolences, describing Sir David as "a decent man and respected Parliamentarian".
Sir Keir Starmer pays tribute to Sir David
She added: "A tragic day for our democracy. My thoughts and prayers are with David's family."
Two more former prime ministers paid tribute, Tony Blair and John Major.
Mr Blair, who entered Parliament along with Sir David in 1983, said he was "shocked and horrified" by the death.
"Though on opposite political sides I always found him a courteous, decent and thoroughly likeable colleague who was respected across the House. This is a terrible and sad day for our democracy."
Mr Major released a statement, which said: "This is truly heartbreaking news of a good and decent man who - for over 30 years - was a dedicated public servant. My heart goes out to his family."
Sir Roger Gale, who was also first elected at the same as Sir David, paid tribute to his friend, saying "David died doing what David always did - looking after his constituents".
Labour Party leader Sir Keir Starmer tweeted: "Horrific and deeply shocking news. Thinking of David, his family and his staff."
His deputy Angela Rayner tweeted: "I'm horrified by the reports regarding David Amess and an incident at his constituency surgery today.
"We don't know the details yet but on behalf of all of us in the Labour Party I want to say all of our thoughts are with David and we all hope that he pulls through and is ok."
Essex Police said anyone with information should contact the force quoting incident 445 of 15 October.