British police said one of two men arrested over a stabbing attack on a London-bound train has been released without charge.
The only remaining suspect is a 32-year-old British man who remains in custody on suspicion of attempted murder.
Police said earlier that two men, aged 32 and 35, were arrested after the attack that left 11 people hospitalized. One victim remains in a life-threatening condition, a member of train staff whom police say saved lives with his "heroic" actions.
Police have dismissed speculation that the attack was terrorism-related and said two victims remain in a life-threatening condition.
The suspects, a 32-year-old Black British man and a 35-year-old man of Caribbean descent, were arrested eight minutes after the first emergency calls were made at 7:42 p.m. from aboard the train, where passengers had reported scenes of panic and chaos with many running through the carriages and some seeking safety in the toilets.
"This is a shocking incident and my thoughts are with those who have been injured and their families," British Transport Police Superintendent John Loveless said outside the station in Huntingdon in eastern England where the train halted soon after the attack.
"There is nothing to suggest this is a terrorist incident," he added.
Loveless also gave an update on the wounded, reducing the number in life-threatening condition from nine to two. He said four of them were discharged and that one other person arrived at the hospital, taking the overall number treated to 11.
After its emergency stop in Huntingdon, a market town around 120 kilometers (75 miles) north of London, bloodied and confused passengers spilled out of the train. Dozens of police waited, some of them armed, and the two suspects were quickly arrested, Loveless said.
During the immediate response to the attack, police 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 That declaration was later rescinded but no motive for the attack has been disclosed.
"At this early stage it would not be appropriate to speculate on the causes of the incident," Loveless said.
The attack took place as the 6:25 p.m. train from Doncaster in northern England to London's King's Cross station was about halfway through its two-hour journey, having just departed from a stop at Peterborough.
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 - Saturday was the day after Halloween. But as passengers pushed past him to get away, he noticed his hand was covered in blood from a chair he had leaned on.
Following reports that some of those on board the train put themselves in harm's way to protect others, Home Secretary Shabana Mahmood praised the "exceptional bravery of staff and passengers on the train."
King Charles III said he and his wife, Queen Camilla, sent their sympathies and thoughts to those affected and that they were "truly appalled and shocked to hear of the dreadful knife attack."
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.
British Transport Police's Loveless said passengers will see a "high visibility presence of police officers at stations and on trains" on Sunday.
