A factory fire near the railway line between Todmorden and Rochdale has caused "severe disruption" to services this morning.
There will be no services on that part of the route until at least 9am because it is "unsafe" to run them, Northern said.
"This means services between Manchester Victoria and Leeds are severely disrupted," a spokesperson said.
Bus replacement services have been requested at affected stations.
Train services from Leeds will terminate at Todmorden, and journeys from Manchester Victoria will stop at Rochdale.
Blackpool North services are unaffected.
Northern customers’ tickets will be accepted on Metrolink's Manchester to Rochdale service and the First TransPennine Express Manchester to Leeds journeys.
Details about the fire are unclear at this time.
Additionally, due to safety checks being made between Leeds and Bradford Interchange some lines are blocked, Northern said.