Eleven people were injured, with one LNER rail staff member in a life-threatening condition, following a knife attack on a London-bound train.
The incident occurred shortly after the train departed Peterborough, leading to an emergency stop at Huntingdon station.
A 32-year-old man from Peterborough has been arrested on suspicion of attempted murder and remains in custody.
British Transport Police confirmed there is no indication the attack is terror-related and praised the heroic actions of the injured staff member, which “undoubtedly saved people’s lives”.
Witnesses described hiding and barricading themselves during the rampage, which saw armed officers use a Taser to subdue the alleged attacker.