'I looked at my hand and it was covered in blood'

Alistair Day, who was travelling back to Hertford having watched Nottingham Forest, was on the train when the attack happened - having narrowly missed his original connecting service.

He joined others and hid in the train's buffet carriage as a fellow passenger confronted a man with a knife.

"I was just by the buffet car. It was odd. I was at the end of the carriage. All these kids were running up and I thought it was like a prank - Halloween or students," he said.

"Then they're getting louder and louder any sorts of people with blood on them [appeared] and I thought, 'Oh, bloody hell, this is not good.'

"I saw a guy flailing out - a fracas with arms going everywhere. I didn't see him that well because there were people in front of him.

"My initial thought was I'm going to sit there and try and do something but I changed my mind.

"We all jumped up and everyone kept running but I was next to the buffet car and the guys in the carriage were trying to close up the shutters and everything.

"So I said, no, you've got to let us in here. So I jumped in there - there were about 12 of us in there.

"I was the first one in, so I was in the corner. A young woman who I spoke to afterwards was by the window and the guy was at the window with his knife trying to get in. Obviously we'd locked it by then."

Joe, who was also travelling back from the Nottingham Forest v Manchester United match, said the scenes were "like something out of a movie".

The 24-year-old, from Peckham in south-east London, said: "I was texting my friends about my plans for that night and then people came rushing through from the carriage, running through, saying, 'You need to run, you need to run'.

"At first it didn't really register what was going on.

"And then quickly, I just dropped my stuff and I started running along with them.

"And then I looked back, and I could see this guy - he was quite a tall, black male, and he had a bloodied knife.

"You just looked around and there was blood just everywhere."

Joe continued: "We kept moving through the train. We could see him behind us coming through.

"The scariest thing was that I knew that because the stops at this stage of the journey are just Stevenage and King's Cross there's quite a lot of big distances between stops.

"So we had no idea how long we were going to be on the train for.

"The thing that was in my mind was we're running through this train now but what if we run out of carriages to run through? What if we reach the end of the train? What happens there?

"It all happened very quickly. I was just in a fight or flight mode really."

Olly Foster, a passenger on the train, told the BBC he initially heard people shouting "run, run, there's a guy literally stabbing everyone", and believed it might have been a Halloween related prank.

He said within minutes, people started pushing through the carriage, and he noticed his hand was "covered in blood" as there was "blood all over the chair" he had leaned on.

An older man "blocked" the attacker from stabbing a younger girl, leaving him with a gash on his head and neck, Mr Foster said.

Passengers around him used jackets to try to staunch the bleeding.

He added that the only thing people in his carriage could use against the attacker was a bottle of whiskey, leaving them "staring down the carriage" and "praying" that he would not enter the carriage.

Although it lasted 10-15 minutes in total, Mr Foster says the incident "felt like forever".

Describing the scene when he got off the train, he said: "There were three people bleeding severely. One guy was holding his stomach and there's blood coming from his stomach and going down his leg.

"He was going 'help, help, I've been stabbed'."

The train's only other scheduled stop before King's Cross was due to be at Stevenage.

Wren Chambers, who was due to get off in the Hertfordshire town, said they first became aware something was wrong when a man bolted down the carriage with a bloody arm, saying "they've got a knife, run".

Wren said they and a friend ran to the front of the train and saw a man who had collapsed on the floor.

Wren said they felt "stressed and pretty scared" once they knew what was happening, but they were eventually able to get off the train unharmed.

"There was quite a lot of blood on the train, there was some on my bag, some on my jeans," she told BBC Radio 5 Live.

"As soon as the train stopped and people got off most of them ran outside trying to get away from it, because we knew the attacker was still inside on the train."

London Underground worker Dean McFarlane told the BBC that he saw the train pull into Huntingdon railway station at 20:00 with a passenger bleeding.

He said that on arrival, he saw multiple people running down the platform bleeding, with one man in a white shirt "completely covered in blood".

He said he grabbed people and told them to leave the station, and tried to assist passengers who he believed were having panic attacks.