Here's what we know so far about the investigation into the fatal stabbing of Essex MP Sir David Amess.
A 25-year-old British man is being held in custody on suspicion of murder
A knife has been recovered from the scene and it is believed the man acted alone, Essex Police says
The attack has been declared a terrorist incident by police
The early investigation has revealed "a potential motivation linked to Islamist extremism", according to Metropolitan Police's Counter Terrorism Command.
Government sources tell the BBC the suspect is a UK national who, from initial inquiries, appears to be of Somali heritage
The Metropolitan Police says officers are carrying out searches at two undisclosed addresses in London
They have also appealed for any witnesses or anyone with CCTV, dashcam or doorbell footage to come forward
Detectives and the security service MI5 will be examining any mobile phones and devices and delving deeply into the life of the suspect to understand how he reached his mindset, BBC home and legal correspondent Dominic Casciani says
We've got more detail on what we know about the investigation so far here.
We must take serious steps - government adviser
James WoodcockCopyright: James Woodcock
Walney, independent adviser to the government on political violence and disruption, says he can imagine a discreet police presence at constituency
events would be an attractive option for many MPs.
The former Labour MP told BBC Radio 4's PM programme: “It is not
simply the awful tragic violent act that took the life of David Amess and my
friend Jo Cox.
"It is also that sense of intimidation, if that prevents people
coming into parliament in future, and puts pressure on people to act
differently or step down that in itself is a huge attack on our democracy and
it’s something that we must be concerned about and take serious steps to
Asked if he will make any recommendations for security measures
to ensure MPs physical safety, Walney says he thinks we will see the
Speaker of the House of Commons stepping up the levels of security.
Police at MP surgeries could put people off going - Abbott
A Labour MP has
expressed caution over the idea that constituency surgeries should be observed
by police officers for protection, following the death of Sir David.
who served as Shadow Home Secretary under Jeremy Corbyn, says it could risk putting people off from visiting their local MP.
Caroline Wyatt on BBC Radio 4 PM, she says: "I’ve been talking to colleagues - there was one in North London who
was telling me that because of death threats she had a police officer outside
her advice session - and a police car in fact. Well of course the number of
people coming to see her dropped right down.
"You don’t want to have a set-up
which is so off putting to ordinary people that just want help. So I wouldn’t
support airport-style screening.
“I would prefer, going forward, to meet constituents behind a screen, as we have now for Covid
and so on - that might be quite complicated to arrange but at least you know
someone’s not going to just lean over the desk and stab you, which could happen
Community gathers for vigil in Southend
People in Southend came together this afternoon at the town's Civic Centre to hold a vigil and reflect on the life of the MP David Amess and light candles.
What's happened since Sir David Amess's death?
As tributes continue to pour in for Essex MP Sir David Amess let's take stock of what's happened since he was killed while meeting constituents in Leigh-on-Sea yesterday.
Police say they are treating the stabbing as terrorism which is potentially motivated by Islamist extremism
A 25-year-old man has been arrested on suspicion of murder and officers are searching two addresses in London
Prime Minister Boris Johnson, Labour Leader Sir Keir Starmer and Home Secretary Priti Patel paid their respects at the scene
Sir David's death has sparked discussion over the safety of MPs holding surgeries in their constituencies, with some continuing to meet people today
Patel said MPs security was being reviewed
People have gathered near the church where he was killed to leave flowers and messages. Tributes have also been left at his local Conservative club and at Westminster
'No right or wrong answer' on MPs' surgeries
Labour MP Naz Shah says there is "no right or wrong answer" over whether or not MPs should continue holding their surgeries.
The Bradford West MP - who has received death threats in the past - says the attack on Sir David "could have happened to any of us".
"I just think you've got to respect every MP - some will have the 'Yes, we're going to carry on' view, and some people won't feel comfortable."
Amess will 'be fondly remembered by West Papuans'
The West Papua independence leader Benny Wenda has sent his condolences to the family of Sir David Amess.
He says he was one of the first MPs to sign the Westminster Declaration for West Papua and would "always be fondly remembered by West Papuans".
The Westminster Declaration calls for an internationally supervised vote on independence from Indonesia for West Papua and has been signed by parliamentarians around the world.
Some of the BBC's international correspondents explain what the situation is like in other countries.
BBC South American correspondent Katy Watson says being an open, accessible people's representative in the major cities of Brazil - Sao Paolo and Rio de Janeiro - where wealth and inequalities are polarised, politicians are more likely to be flanked by bodyguards.
Brazil is deeply divided politically and President Jair Bolsonaro was stabbed during his leadership campaign.
Being an MP in India - the world's largest democracy - comes with a lot of privileges, a security detail is one of them, writes Vikas Pandey in Delhi.
In recent years, attacks on politicians have taken the form of ink-throwing and slapping.
But a number of politicians, including former PMs Indira Gandhi and Rajiv Gandhi, have lost their lives in violent attacks.
In the Netherlands, Dutch lawmakers do not hold surgeries and only a select few Dutch politicians, including the anti-Islam leader, Geert Wilders, have protection.
The prime minister, Mark Rutte, pictured below, has been seen cycling to meetings.
The fuel poverty charity National Energy Action describes Sir David as "a true public servant".
The charity said the MP would be remembered for his bill aimed at eliminating fuel poverty - the Warm Homes and Energy Conservation Bill.
The bill required the government to publish and implement a strategy to reduce fuel poverty and became law in 2000.
A spokesperson for the NEA said Sir David's family could "take some small comfort from knowing the huge positive difference he has made".
"Millions of people across the UK are now better supported through national policies and programmes than before he started his campaign and he has directly helped millions of people to be warmer and safer in their homes."
Attack was 'attempt to fuel fear' - London mayor
London Mayor Sadiq Khan says his thoughts are with Sir David Amess' family at "this time of unimaginable grief".
He describes the Essex MP as "a brilliant, kind, dedicated public
servant, widely liked and respected across the political divide".
He adds: "I’m utterly disgusted
by this attack on our democracy.
“Like with the murder of my dear friend Jo Cox five years ago, it appears that the horrific killing of Sir David Amess was another attempt to divide us, to fuel fear and to change how we treat one another."
"Our response must be to stand united in defiance and stay true to our values and way of life."
MP: 'David would not have wanted us to cancel surgeries'
We've been reporting that some MPs are holding their usual surgeries in their constituencies following the death of Sir David Amess.
Among them is Craig Williams, MP for Montgomeryshire, who met voters alongside his Conservative colleague from the Welsh Parliament, Russell George.
Kieran Mullan, the Tory MP for Crewe and Nantwich, tweeted: "Surgery today, we must not let people force us to do things differently. David would not have wanted that."
UK terror threat level unchanged
Home Affairs Correspondent
There's no indication that the national terrorism threat level is going to be changed to a higher level in light of the attack.
The threat level is currently "substantial" which is in the middle of the five tiers.
It means the Joint Terrorism Analysis Centre, which is part of MI5, thinks that an attack is "likely".
It's been at that level since February.
The two levels above it are typically triggered when there are ongoing concerns among counter terrorism leaders of an emerging plot or remaining questions about an incident that's already taken place.
Southend Mosques remember Sir David's 'warmth, selflessness and kindness'
Members of Southend-On-Sea’s Muslim communities are paying tribute to Sir David Amess as a community leader, friend and mentor.
A joint statement from all the mosques in the town says: "He shared in our happiness, by attending our weddings and functions and he was there for us in our times of need. We will all miss him dearly, but his legacy of public service will live on, as will memories of his warmth, selflessness and kindness."
It says: "Sir David’s murder was an indefensible atrocity, commited on the grounds of a place of worship and we condemn it in the strongest possible terms.This act was committed in the name of blind hatred, and we look forward to the perpetrator being brought to justice."
Ruhul Shamsuddin, joint secretary of Essex Jamme Masjid
remembers Sir David as "a tremendous force for good" and "a truly
"It’s an honour to say I’ve known him my whole life. I’ve lost not just a community leader, but a
family friend and mentor.”
Irish president offers condolences
Getty ImagesCopyright: Getty Images
President of Ireland, Michael D Higgins, has sent his condolences to Sir David's family.
He said he was killed while carrying out a fundamental role of a politician - helping their constituents.
He offered his "deepest sympathies to the family, friends, colleagues in Parliament and constituents" of Sir David.
He also extended thoughts to the family of the late Jo Cox MP, murdered just over five years ago in her constituency of Batley and Spen.
"On behalf of the Irish people, I send them our deepest sympathies."
Iranian pro-democracy group mourn loss of Sir David
The British Committee for Iran Freedom (BCFIF) has issued a statement condemning the "vicious attack, which was an assault not only on Sir David, but also on democracy in the UK".
Sir David was a champion of human rights and democracy in Iran for more than three decades. He consistently spoke in support of the Iranian people’s democratic aspirations and the Iranian Resistance movement, NCRI, the BCFIF said.
"One of the proudest things I have ever done in my political career is to support the National Council of Resistance of Iran which calls for the Iranian regime to be replaced with a safer and more democratic government," Sir David said on 6 September.
In an email to the BBC, supporter Jahed Madumi wrote: "With great sorrow I
heard about Sir David Amess' loss.
"As an Iranian I have to say that he was a
great friend of our nation, and he always defended the freedom for the people
Mr Amess is seen above with the British delegation during the Conference In Support Of Freedom and Democracy In Iran in Paris in 2018.