Counter-terrorism police in the UK are involved in an investigation into a mass stabbing on a train in which nine people sustained life-threatening injuries.
Police said there have been no fatalities so far, adding that a tenth person suffered non-life-threatening injuries.
A man with a knife is believed to have been shot with a taser by police after the incident on board a high-speed train after it left Peterborough station in Cambridgeshire yesterday.
British Transport Police (BTP) said two people have been arrested in connection with the stabbings.
In a statement, the BTP said that at 7.42pm yesterday it was "called to reports of a multiple stabbing on board the 6.25pm train service from Doncaster to London King's Cross".
"Officers immediately attended Huntingdon station alongside paramedics," it said.
"Armed police from Cambridgeshire Police boarded the train and arrested two people in connection to the incident who have been taken to police custody," it added.
The BTP said: "This has been declared a major incident and Counter Terrorism Policing are supporting our investigation whilst we work to establish the full circumstances and motivation for this incident."
Chief Superintendent Chris Casey said the British Transport Police are "conducting urgent enquiries to establish what has happened".
"At this early stage it would not be appropriate to speculate on the causes of the incident," Chief Supt Casey said, adding "it could take some time before we are in a position to confirm anything further".
British Prime Minister Keir Starmer described the incidents as "deeply concerning".
"My thoughts are with all those affected, and my thanks go to the emergency services for their response," he added.
