Superintendent John Loveless, of the British Transport Police, said it would not be appropriate to "speculate on the causes of the incident" for the time being.
He said: "This is a shocking incident, and my thoughts are with those who have been injured and their families. "At 19:42, we were called to reports of a multiple stabbing on board the 18:25 LNER service from Doncaster to King's Cross. Officers immediately attended Huntingdon station alongside paramedics, where armed police from Cambridgeshire Police boarded the train and arrested two people within eight minutes of the first 999 call. We declared a major incident yesterday, and counter terrorism policing were initially supporting our investigation. However, at this stage, there is nothing to suggest this is a terrorist incident. At this stage, it would not be appropriate to speculate on the causes of the incident. The station remains closed, but we expect trains to be passing through the station from this morning. Passengers will see a high visibility presence of police officers at stations and on trains throughout today who are there to reassure the public and respond to any concerns."