Two men born in Britain are suspected of carrying out the Huntingdon train knife attack which is not believed to have been motivated by terrorism, police have said.
British Transport Police (BTP) said two people remain in a life-threatening condition following the bloody rampage on a high-speed train on Saturday evening.
Superintendent John Loveless said one suspect is a black British national and the other is a British national of Caribbean descent. Both men, aged 32 and 35, were born in the UK.
The two suspects remain in separate police stations for questioning, Mr Loveless said.
The force declared a major incident and said the pair were arrested after the 6.25pm train service from Doncaster to London King’s Cross was stopped at Huntingdon station.
The King said he is “truly appalled and shocked to hear of the dreadful knife attack” adding: “Our deepest sympathy and thoughts are with all those affected, and their loved ones.”
Mr Loveless said 11 people had been treated in hospital, and after nine originally presented with life-threatening injuries, four have now been discharged.
Commenting on whether the incident was terrorism, he told reporters: “British Transport Police declared a major incident yesterday, and counter-terrorism policing were initially supporting our investigation.
“However, at this stage, there is nothing to suggest that this is a terrorist incident.”
Mr Loveless said armed police officers and paramedics attended Huntingdon station and boarded the train, arresting the two suspects within eight minutes of the 999 call being made.
Home Secretary Shabana Mahmood praised the “exceptional bravery of staff and passengers on the train”.
She also confirmed the incident was not being treated as terrorism.
