There were severe delays after a train guard was attacked by two men on the Clitheroe to Manchester service.
The attack, which left the guard with facial injuries, led to a rail service being terminated and severe delays on the line.
The incident happened as the train was travelling from Clitheroe to Manchester Victoria on Saturday evening.
A spokesman for British Transport Police said: "Officers were called to Bromley Cross rail station following reports of a person assaulted. The incident happened on Saturday, February 18th, on the platform. The call came into police at 5-50 pm. One man was attacked by two men. The man suffered bruising and a cut to his lip.
"Officers are investigating the incident.
"If anyone has any information please contact British Transport Police on 0800 40 50 40 or text 61016 citing reference 452 of 18/02/17"