Dozens of passengers were led to safety after the train they were travelling on derailed in a Pennine tunnel.
The leading carriage of the First Transpennine Manchester Airport to York service came off the rails near the village of Summit, near Littleborough.
British Transport Police said 45 passengers and two crew were led to safety from the scene on Tuesday at 0140 GMT.
The train remained upright and there were no casualties, police said.
British Transport Police said their officers, a team from Lancashire Constabulary and paramedics made their way to the site.
Experts from the Rail Accidents Investigation Branch are working to establish the cause of the incident.