British Transport Police and paramedics were at the scene of the incident between Hebden Bridge and Burnley Manchester Road stations earlier this afternoon.
The line was blocked, causing disruption to Northern services between between Leeds and Manchester Victoria; Kirkby/Wigan Wallgate and Blackburn, and York and Blackpool North
A replacement bus was running between Hebden Bridge and Todmorden until the line was reopened.
In its latest update, National Rail said: "The emergency services have dealt with an incident between Hebden Bridge and Burnley Manchester Road.
"Trains between Halifax and Rochdale/Burnley Manchester Road are returning to normal but may still be delayed, revised or cancelled."
It said disruption was likely to continue until around 4pm at least.