Nine people have been left with life-threatening injuries and a tenth sustained a non-life threatening wound after the stabbing on a train near Cambridge in the United Kingdom.
Witnesses say victims of a mass stabbing on board a train bound for London were forced to flee their alleged attacker through the carriages.
Nine people have been left with life-threatening injuries and a tenth sustained a non-life threatening wound after the stabbing on a train near Cambridge in the United Kingdom at 7.42pm (6.42am AEDT).
Two people have been arrested in connection with the incident, police said.
READ MORE: Nine people fighting for life in hospital after mass stabbing on UK train
READ MORE: Man charged with murder after woman found dead in Hunter Valley home
A witness to the stabbing told the BBC he saw a man raise the alarm to fellow passengers as he bolted through the carriage with a bloodied arm.
The man recalled hearing him say "they've got a knife, run".
He also said another passenger was seen collapsed on the floor of the train.
Another witness, who was on the platform at Huntingdon when the train approached, said multiple people were bleeding as they disembarked the train.
London Underground worker Dean McFarlane told the BBC one victim was wearing a white shirt "completely covered in blood".
Passer-by Cassie saw police at the scene as the train arrived at Huntingdon station.
"We thought it was a train crash," she told Cambridgeshire Live.
"[There were] more emergency services than I have ever seen."
Some told Sky News of people trampling over each other, and some hiding in the toilets to escape.
Another saw one of the attackers being Tasered by police before being arrested.
Olly Foster told the BBC he heard people shouting "run, run, there's a guy literally stabbing everyone", but he believed it might have been a Halloween prank.
He then saw a man "covered in blood" and saw "blood all over the chair" he had leaned on.
A man "blocked" the attacker from stabbing a girl, leaving him hurt, he said.
It was the 6.25pm service travelling from Doncaster to London King's Cross, British Transport Police confirmed.
British Transport Chief Superintendent Chris Casey described the stabbing as "shocking" and said it would take some time before more information about the incident becomes clear.
"This is a shocking incident and first and foremost my thoughts are with those who have been injured this evening and their families," Casey said.
"We're conducting urgent enquiries to establish what has happened, and it could take some time before we are in a position to confirm anything further.
"At this early stage it would not be appropriate to speculate on the causes of the incident."
Two people were arrested at the station, which is around 120km north of London.
Huntington MP Ben Obese-Jecty told the BBC the attack happened after the train left Peterborough.
"Plato" was declared initially - the UK code word used by and emergency services when responding to a "marauding terror attack" - before it was later rescinded.
Counter-terrorism officers are assisting in the investigation however police have not yet established a motive.
DOWNLOAD THE 9NEWS APP: Stay across all the latest in breaking news, sport, politics and the weather via our news app and get notifications sent straight to your smartphone. Available on the Apple App Store and Google Play.
UK train stabbing suspect released as 'hero' fights for life
Son 'shattered' after mum allegedly killed by boyfriend in Hunter Valley
Wedding ruined as guests shelter in shed flattened in wild storm
NSW billionaire buys Brisbane's most famous pub for $50 million
'Let's get the machetes': Melbourne dad's terrifying run-in with teens
Cruise cancelled after passenger left behind on island died alone
Eight minutes to put 11 in hospital: What's known about UK train stabbing
More storms hammer south-east Queensland after nine hurt by hail
Two new suspects charged over Louvre jewels heist
Power cut to hundreds as severe storm pummels Queensland
'Race against the clock': A peek behind the curtain in the BoM office
'Morons': Liam Gallagher blasts fan after first Oasis gig in Melbourne
