UK police were Sunday investigating a mass stabbing on a London-bound train that injured several passengers, with a British national the sole suspect in an incident not being treated as a terrorist matter "at this stage".
Here's what we know so far:
- What happened? -
Police were alerted to an emergency on board a train between Doncaster, a town in northeast England, and London's King's Cross Station -- a typically busy route -- at around 7:40 pm (1940 GMT) on Saturday night.
The train was stopped at Huntingdon station in Cambridgeshire, where armed officers backed by police cars, a fleet of ambulances and two air ambulances swarmed the station in the eastern England market town.
"Police boarded the train and arrested two people within eight minutes of the first 999 call," Superintendent John Loveless from the British Transport Police told reporters at a briefing on Sunday.
In an update later Sunday the police said they had released one of the two arrested men "with no further action".
While 10 people were initially taken to hospital, five were later discharged. One victim, a member of the rail staff who tried to stop the attacker, remained in a life-threatening condition late on Sunday.
The head of the transport union RMT, Eddie Dempsey, commended the train crew, driver and operators "who quickly assisted in diverting the King's Cross-bound train into Huntingdon station".
"The actions of the member of rail staff were nothing short of heroic and undoubtedly saved people's lives," the police said.
- What the witnesses saw -
Witnesses on board the train have described scenes of chaos and horror as an attacker with a large knife stabbed passengers on board.
Witness Olly Foster told the BBC that he heard people shouting "run, run, there's a guy literally stabbing everyone". and initially thought it was a Halloween-related prank.
But passengers then started pushing through the carriage, Foster said, adding that his hand was "covered in blood" from stains on a chair he had been leaning on.
Foster said he saw an older man block the assailant from stabbing a younger girl, adding the attack "felt like forever" though it lasted only minutes.
Another witness told The Times newspaper there was "blood everywhere" as people hid in the washrooms.
Others told Sky News they saw a man holding a large knife on the platform after the train halted. They then saw the man restrained by police.
Prime Minister Keir Starmer said the "appalling" incident was "deeply concerning", while King Charles III said he was "truly appalled and shocked" by the attack.
- Those arrested -
Police said they arrested two British citizens on suspicion of attempted murder.
But after releasing a 35-year-old on Sunday after concluding that "he was not involved", the remaining suspect is "a 32-year-old man, a Black British national", the police said.
"He is from Peterborough and it is known that he boarded the train at Peterborough station," in eastern England, the police added in their late Sunday update.
Earlier, Loveless said that the attack's motive was still being probed, but added that "at this stage, there is nothing to suggest this is a terrorist incident".
Huntingdon station remained closed and cordoned off on Sunday, with the train, now a crime scene, still standing at the platform, which was empty except for police and forensic officers.
Police and interior minister Shabana Mahmood underlined that both suspects were born in the UK, following speculation on social media.
Recent attacks have seen the rapid spread of misinformation about the identity of the perpetrators, with social media accounts quickly blaming such events on immigrants or asylum seekers.
London North Eastern Railway, which operates along the route, warned of ongoing disruptions. UK media reported that there will be a "surge" in police presence at major rail terminals including in London and Manchester, citing government sources.
Multiple passengers at King's Cross station on Sunday told AFP they were familiar with the route -- popular with commuters -- on which the attack took place.
"I felt quite anxious today because we do the exact same route as the incident last night," said product manager Georgia Johnson, 30.
"But now it has happened, I trust they'll do everything they can to stop it happening again."
- Knife crime in the UK -
Knife crime in England and Wales has increased since 2011, according to official government data.
While Britain has some of the strictest gun controls in the world, rampant knife crime has been branded a "national crisis" by Starmer.
His Labour government has tried to rein in the use of knives as a crime weapon.
A series of high-profile knife attacks have shaken the country in the last year, including the murder of three girls at a dance class in Southport in July 2024, one of the country's worst mass stabbings in years.
Two people were killed -- one as a result of misdirected police gunfire -- and others wounded in a stabbing spree at a synagogue in Manchester at the start of October.
And a man appeared in a London court on Thursday, charged with murder after a stabbing attack in broad daylight, which left one dead and two injured.
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