Police have released CCTV images of four men they want to identify after two passengers were assaulted at Shipley station.
British Transport Police said its officers were investigating a disturbance caused by a group of men at the station shortly before 11.30pm on June 28.
A spokesman said: "When a train pulled in, the group then became aggressive to two passengers, assaulting them by punching them multiple times to the head.
"One of the victims then fell to the floor where they were kicked multiple times.
"Officers would like to speak with the four men in these CCTV images as it is believed they may have information which could help them investigate."
Anyone with information is asked to send a text to 61016 or call 0800 40 50 40, quoting reference 711 of 28/06/2018.
Alternatively, call Crimestoppers anonymously on 0800 555 111.