As we've been reporting, the police have just given a statement to the press about the death of Sir David Amess.

Here's a reminder of what we know:

• The MP for Southend West was meeting constituents at Belfairs Methodist Church in Leigh-on-Sea, Essex, when he was stabbed several times
• A 25-year-old man was arrested on suspicion of murder after officers arrived at the scene and a knife was recovered

• No details have been released about this man. He remains in custody and police said they were not looking for anyone else
• Counter-terrorism police are leading the investigation into the incident. They will "determine whether or not" this was terrorism

We've got more details here.

Image source, EPA

Richard Beecham
Bradford Political Reporter

Image source, PA Wire

A Leeds city councillor says new security measures have been brought in, external for local authority members this afternoon, following Sir David's death.

Paul Wray, a Labour councillor for Hunslet and Riverside, tweets that "safety advice has been issued" by the Council and that "until further notice, there will be uniformed police presence" at his advice drop-in sessions.

Wray also says he is "ending all house visits".

“It is sad this extra security will be needed, but like many councillors and MPs – I refuse to not do my duty and I will continue to provide the service I was elected to provide. Democracy and accountability must always win," he adds.

Mr Harrington says it is a "tragic day for the family and colleagues of Sir David, the community of Southend and indeed for the whole of Greater Essex".

"Sir David has dedicated his life to serving the communities of Essex and Southend and today he was simply dispensing his duties when his life was horrifically cut short," he says.

He says officers "endured a longstanding and positive working relationship" with the MP and will work "around the clock to ensure justice is delivered".

Specially trained family liaison officers are providing support for Sir David's family, he says, asking people to respect their privacy.

And he urges anyone with information about the incident to contact the police.

Mr Harrington says officers arrived at the scene "within minutes".

"This was a difficult incident but our officers and paramedics... worked extremely hard to save Sir David," he says.

"Tragically he died at the scene."

The 25-year-old man was arrested on suspicion of murder, Mr Harrington says. A knife was also recovered at the scene.

Mr Harrington adds that the investigation "is in its very early stages, and is being led by officers of the specialist Counter Terrorism Command."

"We made it clear at the time of the incident that we did not believe there was any immediate further threat to anyone else in the area," he adds.

"It will be for investigators to determine whether or not this is a terrorist incident."

Chief Constable Ben-Julian Harrington says that when officers arrived at the scene, Sir David had suffered "multiple injuries".

A 25-year-old man was arrested and remains in custody.

We're expecting to hear any moment now from police about the death of Sir David Amess.

We'll be bringing you the latest updates when we get them.

You can watch it live on the BBC news channel at the top of the page (if you're in the UK)

The Conservative leader of Essex County Council, external, Kevin Bentley, said he learned of Sir David's death with "great shock and sadness".

"We worked closely with Sir David over the years, during his period as MP for Basildon up until April 1997 and latterly as MP for Southend West within the neighbouring Southend-on-Sea Council area," the councillor said.

"He was a man who was never afraid to voice his views, passionate in his beliefs and straightforward in how he articulated them.

"He will be greatly missed in Essex and at Westminster. Our thoughts are with his family at this very difficult time."

Image source, Reuters

Former prime minister Tony Blair has said he is "shocked and horrified" by the murder of Sir David.

"David and I came into Parliament together in 1983," he said in a statement.

"Though on opposite political sides I always found him a courteous, decent and thoroughly likeable colleague who was respected across the House," he wrote.

"This is a terrible and sad day for our democracy."

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Andrew Rosindell, Conservative MP for Romford, says in a tweet that he is "utterly devastated" by Sir David's death.

Sir Keir Starmer says it is a "a dark and a shocking day", and notes that "heartbreakingly, we've been here before".

"Informed by his faith, Sir David had a profound sense of public duty and he was highly respected and much liked across the Houses of Parliament on all sides, and within the Christian community," he says.

"There's a very profound sense of loss, I think, across politics, across faith and up and down the country."

Asked what he thinks needs to happen in terms of security for MPs in surgeries, he says: "There are many questions, I think, that are still there - but I think today is a day when all of our thoughts and all of our focus are with Sir David's family."

Dominic Casciani
Home Affairs Correspondent

Scotland Yard detectives and the security service MI5 are assisting Essex Police - but there's no confirmation that this was an act of terrorism.

What that means is that they are keeping an open mind - at the earliest stages of an investigation, good police work requires officers to follow the evidence, rather than inadvertently narrowing down the avenues open to them to establish why an attack happened.

In the hours to come, murder squad detectives will be interviewing the man who is in custody on suspicion of murder - he was held at the scene and there is no suggestion that he was detained after any kind of struggle.

Other teams will be going to the man's home to carry out a search and also downloading communications from any devices he may own.

That communication evidence may be critical to establishing motive and mindset.

"The murder of an MP, in the course of caring for their constituents, is a deep blow to this country, its citizens and everyone who desires a peaceful and flourishing democracy."

Justin Welby, the Archbishop of Canterbury, wrote this in a strongly-worded statement posted on Twitter, in which he said he was "truly devastated" by Sir David's death.

"The death of a father, husband and friend is agonisingly painful for those who loved him," he wrote.

"He was a devout Roman Catholic whose deep faith fuelled his sense of justice. We are richer for his life, and we are all the poorer for his untimely death," he said.

Former House of Commons speaker, John Bercow, has told the BBC that "the reality is that not much has changed" since the killing of MP Jo Cox in 2016.

Speaking on Radio 4's PM programme, he said: "The vast majority of people would deplore in the strongest possible terms this gross and heinous act.

"It's an unspeakable barbarity but the truth is there is much toxicity in our politics and this should give us pause to reflect on how our politics is conducted in the future."

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But Mr Bercow added that today should be about marking Sir David's life and said he was "was above all a thoroughly decent, likeable and lovable human being".

"What has happened today is both a tragedy and an outrage but he made a mark," he said.

"He made an indelible mark on everybody he met."

Boris Johnson has paid tribute to Conservative MP Sir David Amess in a video statement.

The PM said he was one of the "kindest, nicest, most gentle people in politics".

Sir David, 69, had been an MP since 1983 and was married with five children. Police said a 25-year-old man was arrested on suspicion of murder after the attack at a church in Leigh-on-Sea while the MP met constituents as he did regularly.

Following the attack on Southend West MP Sir David Amess at a constituency surgery, Home Secretary Priti Patel said she would provide an update "in due course" on the safety of MPs.

Writing on Twitter, Ms Patel said: "Questions are rightly being asked about the safety of our country's elected representatives and I will provide updates in due course. My heartfelt thoughts and prayers are with David's family and friends."

The MP for Witham added that "David was not only a fellow Essex MP, but a kind and loyal friend".

"David served the people of Southend with endless passion, energy and integrity," Ms Patel said. "That he was killed while going about his constituency duties is heartbreaking beyond words. It represents a senseless attack on democracy itself."

Image source, Getty Images

Essex Police have released a statement officially confirming Sir David Amess MP was the man attacked earlier.

They say:

• Officers were called to Eastwood Road North, Leigh-on-Sea shortly after 12.05 BST "to reports Sir David, 69, had been stabbed"
• He was treated by paramedics but was pronounced dead at the scene
• A 25-year-old man arrested on suspicion of murder remains in custody
• A knife has been recovered and the force are not looking for anyone else in connection with the attack
• They have appealed for witnesses and those with footage to come forward

Meanwhile, Roger Hirst, the Conservative Police, Fire and Crime Commissioner for Essex, said: “This is a shocking and utterly despicable attack against somebody who was an outstanding MP and has worked tirelessly for their community for many, many years.

"My prayers are with Sir David’s family at this incredibly difficult time.

"I also want to acknowledge the officers who attended the event for their bravery and courage."

The prime minister describes Sir David as "one of the most kindest, nicest, most gentle people in politics".

"He also had an outstanding record of passing laws to help the most vulnerable," he adds, "whether [that was helping] people who were suffering from endometriosis, passing laws to end cruelty to animals or doing a huge amount to reduce the fuel poverty suffered by people up and down the country."

Sir David "believed passionately in this country and in its future", the prime minister says.

"We've lost today a fine public servant and a much loved friend and colleague."

He says everyone is "deeply shocked and heart-stricken" and that his thoughts are with Sir David's family.

The prime minister is paying tribute to his Conservative colleague who was killed today.

He says: "I think all our hearts are full of shock and sadness today at the loss of Sir David Amess MP who was killed in his constituency surgery in a church after almost 40 years of continuous service to the people of Essex and the whole of the United Kingdom."

Trade minister Penny Mordaunt has published a speech given by Sir David Amess at an event at the Royal Albert Hall.

She tweeted: "For those who didn't know Sir David Amess, this will give you a measure of the man."