British Transport Police believe they could have vital information about a vicious assault on a father and son at Stalybridge station.
The incident, which left fellow passengers horrified by what they saw, took place at around 9.30pm on Saturday, 29 November,
Investigating officer PC Jonathan Price said: â€œThe father and son were returning to Huddersfield from Manchester after a football match.
â€œWhen the train arrived into Stalybridge, they were subjected to a vicious and completely unprovoked assault on the platform by three men.
â€œThe father was knocked to the ground, before one of the attackers ran up and stamped on his head with both feet. The son went to the aid of his father, but was knocked unconscious by two other men.
â€œPassengers helped the victims back onto the train, while the attackers fled from the station. The victims were met at Huddersfield by an ambulance, which took them to A&E, where they were treated for bruising to the head and face.â€
Officers urge anyone who recognises the men in the images to come forward to help with the investigation.
PC Price added: â€œThis was a horrific attack. The level of violence was shocking and could have led to more serious injuries. The victims had done nothing to provoke the attack. It is vital we find the men responsible and ensure they are brought to justice. Violence on the rail network will not be tolerated.â€
Anyone with information is asked to contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference PSUB/B12 of 20/01/15. Information can also be passed anonymously to independent charity Crimestoppers on 0800 555 111.