British Transport Police (BTP) have since confirmed they were called to a report on an assault on board a train.
"No arrests have been made in connection to this incident and enquiries are ongoing," a spokesman for BTP added
As emergency services attended the scene, passengers were advised to plan for delays and disruption.
A spokesman for Northern said: "Due to the emergency services dealing with an incident on a train in Carnforth station, train services are being disrupted through the Carnforth area.
"There is also an ongoing signalling problem in the Grange-over-Sands area which may also affect train services.
"Network Rail and the emergency services are en route. Once we have an ETA, we will update this message."
The nature of the incident has not yet been confirmed, but Northern confirmed all disruption had ended at around 1.140pm.
Lancashire Fire and Rescue Service and North West Ambulance Service said they did not attend the incident.
Witnesses, or anyone with information, can contact BTP by texting 61016 or calling 0800 40 50 40, quoting reference number 177 of January 17.
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