A 32-year-old man is now the only suspect after multiple people were stabbed on a train, police have confirmed.

A railway staff member remains in a life-threatening condition following the attack on a train from Doncaster to London King's Cross, which stopped in Huntingdon, Cambridgeshire, shortly before 20:00 GMT on Saturday.

A 35-year-old man, who was arrested at the scene, has been released with no further action after it was reported "in good faith" that he had been involved in the attack. Officers later confirmed this was not the case.

Eleven people were treated in the hospital after the attack. On Sunday evening, British Transport Police (BTP) confirmed five casualties had been discharged.

The force also confirmed the LNER staff member in life-threatening condition had tried to stop the attacker.

"Having viewed the CCTV from the train, the actions of the member of rail staff were nothing short of heroic and undoubtedly saved people's lives," a BTP spokesman said.

The suspect, who is from Peterborough, boarded the London North Eastern Railway (LNER) train at the city's station, the force said.

Dep Chf Con Stuart Cundy added: "Our investigation is moving at pace and we are confident we are not looking for anyone else in connection to the incident."

The force said a knife had been recovered by officers at the scene.

David Horne, managing director of LNER, thanked emergency service workers "for their quick and professional response" and said the company and staff were "deeply shocked and saddened" by the incident.

"Our thoughts and prayers are with everyone affected, particularly our colleague who remains in a life-threatening condition, and their family," he said.

"I would also like to recognise the driver, crew and our operational response colleagues for their bravery and quick actions."

'People were getting trampled on'

Amira Ostalski was on the train with a friend when she saw a person stabbed by a man carrying what appeared to be a large kitchen knife.

"It was like he had a mission to stab anyone he saw right in front of him," she said.

"There was blood everywhere - people were screaming, 'he's got a knife'."

Ms Ostalski said she witnessed someone being stabbed "five or six rows" from her, adding: "I could have been next. People were getting trampled on.

"It was a very busy train, so people were just trying to run away from the attacker, and people were falling, and people were standing on them. It was horrible."

After the conductor managed to open a door at the station, people began to flee.

"I don't think I'll be able to sit on a train anymore," Ms Ostalski added.

The driver of the train has been named as Andrew Johnson.

When the alarm was raised, Mr Johnson was said to have contacted the control room to get the train diverted from the fast track to the slow track, which has a platform at Huntingdon.

Mr Johnson's actions are believed to be why emergency services were able to board the train so quickly.

His quick thinking likely prevented the train from stopping in the middle of nowhere or having to go to the next station, which would have taken 10 to 15 minutes.

A trade union officer said the driver is "very shaken" but "good", and commended him for doing "exactly the right thing".

Nigel Roebuck, from Aslef, said: "The driver did everything he was trained to do, at the right time and in the right way.

"He showed real courage, real dedication, and real determination in the most difficult of circumstances.

"Our thoughts tonight are with his colleague who is still in intensive care."

Another witness, Thomas McLachlan, said: "I will say there were definitely many heroes on that day, many kind people who just wanted to help those around them - people handing out blankets, hand warmers."

Mr McLachlan said he saw one injured man who had been slashed in the face. He heard the person was "trying to protect a young girl from being attacked".

He said: "He took that injury to the face out of protection for her - that's some real selflessness, right there.

"I saw multiple people covered in blood, and seeing how severe their injuries were, I realised this is something really, really bad."