LONDON – A terrifying stabbing spree on a train heading to London from eastern England has left ten individuals in the hospital, with nine facing critical conditions, according to British police on Sunday. Authorities have detained two suspects and are investigating the incident’s underlying cause.

As the train made an emergency stop in Huntingdon, a scene of distress unfolded with injured passengers, bleeding and in shock, disembarking onto the platform where a significant police presence awaited them. This came shortly after reports emerged of multiple stabbings occurring on board.

Armed police swiftly apprehended two individuals at the station.

While the identities and motives of the suspects remain undisclosed, police have confirmed that counterterrorism units are assisting in the ongoing investigation.

“Ten people have been taken to hospital with nine believed to have suffered life-threatening injuries,” stated the British Transport Police early Sunday. “This has been declared a major incident, and Counter Terrorism Policing is supporting our investigation as we strive to uncover the full details and reasons behind this attack.”

The police force said that “Plato,” the national code word used by police and emergency services when responding to what could be a “marauding terror attack,” was initiated. That declaration was later rescinded but no motive for the attack was disclosed.

“We’re conducting urgent enquiries to establish what has happened, and it could take some time before we are in a position to confirm anything further,” Chief Superintendent Chris Casey said. “At this early stage it would not be appropriate to speculate on the causes of the incident.”

The attack took place as the train from Doncaster in northern England to London’s King’s Cross station was about halfway through its 2-hour journey and approaching Huntingdon, a market town a few miles northwest of the university city of Cambridge.

Passenger Olly Foster told the BBC he heard people shouting “run, run, there’s a guy literally stabbing everyone,” and initially thought it might have been a Halloween prank. But as passengers pushed past him to get away, he noticed his hand was covered in blood from a chair he had leaned on.

Emergency services, including armed police and air ambulances, responded quickly as the train drew into Huntingdon. The attack appears to have been contained swiftly after the train arrived at the station, and police officers wearing forensic suits, with a police dog, could be seen on the platform.

Cambridgeshire Constabulary, the local police force, said officers were called at 7:39 p.m. on Saturday to the scene, about 75 miles (120 kilometers) north of London.

British Prime Minister Keir Starmer said his “thoughts are with all those affected” after the “appalling incident.”

Paul Bristow, the mayor of Cambridgeshire and Peterborough, said he had heard of “horrendous scenes” on the train.

London North Eastern Railway, or LNER, which operates the East Coast Mainline services in the U.K., confirmed the incident had happened on one of its trains and said there would be major disruption on the route until Monday.