Nine people were left fighting for their lives and another injured after a stabbing rampage aboard a London-bound train on Saturday evening that witnesses initially mistook for a Halloween prank.

The attack unfolded on the 6:25 p.m. LNER service from Doncaster to King’s Cross as it travelled through Cambridgeshire, prompting an emergency stop at Huntingdon station. Two people were arrested, and counterterrorism officers have joined the investigation, police said.

Passengers described scenes of chaos and panic as people fled from a man wielding a large knife. Some locked themselves in toilets to hide, while others were trampled as they tried to escape.

“When people began to flee down the train carriage shouting ‘run, run, there’s a guy literally stabbing everyone,’ terrified passengers thought it was a Halloween prank,” witness Olly Foster told the BBC.

Foster said he realised the horror was real when he leaned on a chair and found his hand covered in blood. “An older man blocked the attacker from stabbing a younger girl, leaving him with injuries to his head and neck,” he said, adding that other passengers used clothing to try to stop the bleeding. “It felt like forever.”

Another witness told The Times there was “blood everywhere,” while one passenger told The Sun the scene was “like something from a film.”

Police declared a major incident and briefly activated “Plato,” the code used to respond to a marauding terror attack, before later rescinding it. Armed officers boarded the train after it was diverted to a slow line and brought to a stop at Huntingdon about 14 minutes after leaving Peterborough.

A witness told Sky News that officers confronted the suspect. “As they got closer to him, started shouting, like, get down get down,” he said. “He then was waving a knife, quite a large knife, and then they detained him. I think it was a Taser that got him down in the end.”

Ten people were taken to Addenbrooke’s Hospital in Cambridge. British Transport Police confirmed there were no fatalities but said nine victims suffered life-threatening injuries.

“We’re conducting urgent enquiries to establish what has happened,” Chief Superintendent Chris Casey said. “It could take some time before we are in a position to confirm anything further.”

Defence Secretary John Healey told Sky News that early assessments suggest the incident was “an isolated attack.”

Prime Minister Keir Starmer said on X, “The appalling incident on a train near Huntingdon is deeply concerning. My thoughts are with all those affected, and my thanks go to the emergency services for their response.”