UK police say they now consider only one of two men arrested over the mass stabbing on a London-bound train a suspect.
Police initially arrested two suspects after a mass stabbing on a train that left 10 people in hospital, with two of those people currently in a life-threatening condition.
"Detectives investigating a multiple stabbing on a train in Cambridgeshire can this evening confirm a 32-year-old man who was arrested is now being treated as the only suspect," said a statement from British Transport Police.
He remains in police custody on suspicion of attempted murder, it said, adding that he was from Peterborough, where he boarded the train.
Armed police, backed by police cars and a fleet of ambulances, swarmed a railway station in the eastern rural town of Huntingdon, Cambridgeshire, after the alarm was raised about the attack and the train brought to a halt there on late Saturday local time.
Ten people were initially taken to the hospital, with four discharged shortly after.
Transport police confirmed the train was running from Doncaster in the north-east to London's King's Cross Station, a busy route often packed with travellers.
A witness described seeing a man with a large knife and told The Times newspaper there was "blood everywhere" as people hid in the washrooms.
Some passengers were getting "stamped (on) by others" as they tried to run, and the witness told The Times they "heard some people shouting 'we love (you)'".
Witnesses told Sky News they saw a man holding a large knife on the platform after the train halted. They then saw the man Tasered and restrained by police.
UK Prime Minister Keir Starmer said the "appalling" incident was "deeply concerning".
"My thoughts are with all those affected, and my thanks go to the emergency services for their response," Starmer said in a statement on X.

Two people have been arrested after British Transport Police were called to the incident on the train. Credit: Chris Radburn/PA
'Multiple patients'
Armed police were at the scene after being alerted around 7:40 pm on Saturday local time (6.40am Sunday AEDT) just after the train had left the town of Peterborough.
Late Saturday, police were inspecting the train, which was being treated as a crime scene. People were also led away outside the station in space blankets.
The East of England Ambulance Service said on X that it had mobilised a "large-scale response" to Huntingdon station, including ambulances, air ambulances and tactical commanders.
Train operator London North Eastern Railway (LNER) said railway lines were closed while emergency services dealt with the incident.

Train operator London North Eastern Railway (LNER) said all its railway lines had been closed while emergency services dealt with the incident at Huntingdon station. Source: PA
The mayor of Cambridgeshire and Peterborough, Paul Bristow, said on X that he was aware of "horrendous scenes", adding that his "thoughts and prayers (are) with everyone affected".
The identity of the two people arrested was not immediately known, nor was the motive for the attack.
'National crisis'
Knife crime in England and Wales has been steadily rising 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 their use.
Nearly 60,000 blades have been either "seized or surrendered" in England and Wales as part of government efforts to halve knife crime within a decade, the interior ministry said Wednesday.
Carrying a knife in public can be punishable by up to four years in prison, and the government said knife murders had dropped by 18 per cent in the last year.
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 in an attack which shook the local Jewish community and the country.
And a man appeared in a London court on Thursday charged with murder after a daytime stabbing attack which left one dead and two injured.
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