Sir David Amess stabbing: What we know so far
Conservative MP Sir David Amess died after being stabbed multiple times at his Essex constituency surgery, in what police are treating as a terrorist incident.
Here's how the attack unfolded and what we know so far.
What happened?
The MP for Southend West was stabbed at Belfairs Methodist Church in Leigh-on-Sea, in Essex. He was there for one of his regular Friday meetings with his constituents.
Just 15 minutes before the attack, the 69-year-old was standing on the church steps, chatting and laughing with locals.
At about 12:05 BST on Friday, Sir David walked into the church alongside two female members of his staff to meet more constituents.
Local councillor John Lamb said that it was then a man emerged from a small group of waiting constituents and attacked Sir David, stabbing him several times.
Mr Lamb later shared the accounts of Sir David's two assistants.
He described how one was in the room with Sir David taking notes. "All of a sudden there was a scream from her, because the person deliberately whipped out a knife and started stabbing David.
"The other lady, who was getting names from people outside, she came running in and saw poor David had been stabbed."
Police arrived at the scene in Eastwood Road North within minutes where they found the MP with multiple injuries and arrested a man.
"We knew it must be very serious because the paramedics had been working on Sir David for over two-and-a-half hours and they hadn't got him on the way to hospital," Mr Lamb told the PA news agency.
At 14:13 an air ambulance arrived at a nearby sports ground to move him to hospital. However, members of his team began to fear the worst as paramedics remained at the scene.
Shortly before 15:00, Essex Police said Sir David had died.
Who is the suspect?
At 13:50 on Friday, Essex Police confirmed a 25-year-old man had been arrested immediately at the scene on suspicion of murder, and that a knife had been recovered.
Whitehall officials have confirmed to the BBC that the suspect - who is being held at a London police station under the Terrorism Act 2000 - is Ali Harbi Ali, a British national of Somali heritage.
He was born in Southwark in south London and grew up in Croydon, and is the son of a former adviser to a previous Somali prime minister and the nephew of the Somali ambassador to China.
In his teenage years he was referred to the government's extremism programme Prevent but was never a formal "subject of interest" for MI5.
Prevent is the UK's terrorism-prevention programme, which aims to stop people being radicalised.
Teachers, members of the public, the NHS and others can refer individuals to a local panel of police, social workers and other experts who decide whether and how to intervene in their lives.
Engagement in the scheme is voluntary and it is not a criminal sanction. It is thought Mr Ali did not spend long in the programme.
What do police say?
The attack has been declared a terrorist incident by police.
The early investigation revealed "a potential motivation linked to Islamist extremism", according to Metropolitan Police's Counter Terrorism Command.
But it is still not exactly clear why Sir David in particular was targeted, Daniel Sandford, the BBC's home affairs correspondent said.
Ali Harbi Ali was initially detained on suspicion of murder but was further detained under the Terrorism Act late on Friday.
On Saturday, detectives were granted a warrant by magistrates to allow them to keep Mr Ali in custody until Friday 22 October.
The suspect is still being questioned and has not been charged.
Police searches have taken place over the weekend at properties in Lady Somerset Road, in Kentish Town, and Bounds Green Road in north London and Cranmer Road, Croydon.
A post-mortem examination of Sir David has taken place, the police added.
What did witnesses see?
Anthony Finch, who was working nearby, told Sky News: "We arrived to do some work on the adjacent building... and at the point when I was crossing the road I saw an upset lady on the phone saying 'you need to arrive quickly, he's still in the building.'"
He said he had seen armed police, as well as an air ambulance and police helicopter. He told LBC: "It's very odd and it's very distressing, that's for sure."
Lee Jordison, who works for a local butchers and was on the scene shortly after the stabbing, told the BBC everyone in the area was in a state of shock.
"Something like this doesn't happen - not in all the years I've been round this way."
Who was Sir David Amess?
Sir David, who was married with five children, served as an MP for 38 years, initially in Basildon from 1983, before representing Southend West from 1997.
Raised as a Roman Catholic, he was known politically as a social conservative and a prominent campaigner against abortion. He was also a committed campaigner on animal welfare issues, and supported a ban on fox hunting.
The 69-year-old was a Brexit supporter and vocal champion for the town he represented, particularly in his long-running campaign to make Southend a city. He launched a new bid last month, after a city status competition was announced to mark the Queen's platinum jubilee next year.
While he was never a minister, he was a member of numerous Commons committees, including the Health and Social Care and Backbench Business Committees.
Born in Plaistow, east London, in 1952, he went to school in the capital and taught at a school in the city. He was a recruitment consultant before becoming an MP.
He was knighted in the 2015 New Year's Honours List for political and public service.
His family said in a statement that their hearts had been shattered and "nobody should die in that way".
They called on people to show kindness and love and "set aside hatred and work towards togetherness".