A man was repeatedly stabbed in a station car park after challenging a group of passengers who were throwing objects around a train carriage.
British Transport Police (BTP) have launched an investigation and are appealing for witnesses following the New Year's Eve attack on the 28-year-old, who had to undergo surgery for his injuries.
The victim, from Liverpool, had been on the 8.34pm Liverpool Lime Street to Birmingham New Street train when he challenged the group - believed to be one man and four or five women - who had been throwing items around.
After leaving the train at Winsford, Cheshire, shortly after 9pm, he was followed by the man from the group before being repeatedly stabbed in the groin and upper body.
His injuries were not life-threatening and he was taken to safety by another passenger from the train.
The attacker is described as being in his late 20s and of stocky build.
Detective Sergeant Matt Davies, from British Transport Police, said: "Thankfully, the victim's injuries are not life-threatening but he remains in hospital, where he has received surgery for his wounds.
"We are also grateful to the passenger who came to the aid of the victim and took him to a place of safety.
"Our investigation into who is behind this attack continues and we have been at the station today conducting a forensic examination of the scene, local inquiries and reassurance patrols.
"It is vital we now speak to anyone who was on the 8.34pm train out of Liverpool and witnessed the disturbance in the carriage, as well as anyone else who was in the area of Winsford station at 9.10pm and saw what happened.
"I would also appeal to those involved to do the right thing and come forward as soon as possible."
Anyone with information should call BTP on 0800 40 50 40 or text the force on 61016 quoting reference 454 of 31/12.
Alternatively, details can be passed anonymously to the independent charity Crimestoppers on 0800 555 111.