An Australian expat recounted the terrifying moment he witnessed a man allegedly committing a mass stabbing on a British train, moving through the carriages with a weapon in hand.

Matt Kingston was on his way back to his home in London on a train Saturday when chaos erupted as passengers began to flee in panic.

Speaking to Ben Fordham on 2GB radio, Kingston shared that he initially had his back turned, but was jolted by the cries of, “He’s got a knife, run, run.”

Reacting quickly, Kingston removed his headphones and joined the fleeing passengers, heading towards the train’s cafe bar.

Observing the cafe’s steel shutters being drawn, he realized it could serve as a temporary sanctuary.

“I saw train staff shutting the shutters, trying to secure themselves inside, and noticed the door was still ajar… I thought this seemed like a safe option,” he recounted.

The Australian joined nine others crammed inside the small space.

Moments later he watched through a glass screen as Anthony Williams, the 32-year-old man accused of carrying out the stabbings, calmly strolled past holding a large knife.

“It was eerie … I never felt fear and panic like it before,” Kingston said.

He also said a fellow passenger tackled the accused attacker just metres from him.

“This guy off his own bat tried to help someone … he super selflessly helped out.”

Kingston, who has lived in the UK for nine years, had caught the train from its departure point at Doncaster station after spending the day in northern England.

The train was about halfway through its journey and had just left a stop at Peterborough when police began receiving calls about people being stabbed onboard.

Williams was arrested when the train made an emergency stop in the town of Huntingdon in eastern England.

He has since been charged with 10 counts of attempted murder, one of actual bodily harm and one of possession of a bladed article over the attack.