A student has told how she thought she"was going to die" during a mass stabbing on a high-speed train.

Amira Ostalski was travelling to London for a Saturday night out with her friend Vanessa on the"very busy" 6.25pm Doncaster to King's Cross LNER service.

She told Sky News correspondent Dan Whitehead they were"listening to music, just having a good time", when"panic and chaos" broke out in her carriage, Coach G, between Peterborough and Huntingdon.

"I see five rows ahead of us a guy in a white t-shirt just jumps out of his seat," she said."People are screaming, 'he's got a knife'.... I'm guessing he stabbed the person right in front of me."

Ms Ostalski said she came within 2m of the attacker but only caught a glimpse of him, adding:"He was just a black bearded guy wearing all black and a hoody.

"I didn't see the knife he was holding. I'm guessing because it was already in the body or something."

She said she "started running" and was "trying to calm everyone down" because there was a boy, around six years old, who hid in the toilets with his mum.

"Everyone's running. A guy next to me is holding his arm saying he's been stabbed. He was running. I see people covered in blood," she said.

"Everyone was shocked, everyone was terrified. People wanted to know what was going on, everyone's pushing and shoving. Everyone's getting trampled."

Ms Ostalski said she heard some people crying on the phone "in tears and in shock, thinking they're going to be stabbed".

"It was horrific, it was really horrific because we had no idea where he was and the conductor who tried to stop him, he got stabbed as well.

"We felt that we were not safe because we were trying to get the train to stop but it wasn't stopping."

Ms Ostalski said she ran into the buffet car where she picked up a metal tray to protect herself and her friend.

"I was honestly so petrified. I thought in that moment it was the last time I was ever going to be alive. I thought I was going to die," she said.

Ms Ostalski said she saw the attacker again when the train was stopped at Huntingdon station, holding a bottle in his left hand by the door.

"He just looked so calm and I think that was the most terrifying thing," she said.

Police declared a major incident and armed officers can be seen in video footage sprinting along the platform.

Ms Ostalski said she thought she and the other passengers were safe when the train was evacuated.

But when she reached the car park, she turned around and saw the attacker jump the fence and start coming towards them.

"I have to admit, the police came really quickly and managed to detain him," she said.

"I saw them running then took the knife and he got tasered and fell right on the spot."

Two men born in Britain were initially arrested but one has been released, leaving a 32-year-old in custody on suspicion of attempted murder.

Police do not believe the incident was motivated by terrorism.

Eleven people were treated in hospital but police said on Sunday that only one - the member of staff who tried to stop the attacker - was still in a life-threatening condition.

Ms Ostalski said she finally found safety in a taxi but will remember the ordeal for the rest of her life.