Train lines between Manchester Victoria and Rochdale are blocked because of a trespasser on the line.
British Transport Police were called to Mills Hill railway station in Middleton at around 1.30pm on Thursday.
Officers attended and discovered a woman on the tracks.
She was taken to safety.
Northern Rail sent out an alert to passengers at 2pm and warned that disruption would be expected for at least the next 45 minutes.
Train services running through Manchester Victoria and Rochdale may be cancelled or delayed for up to 60 minutes.
Tickets for Northern services are being accepted on the Metrolink.
A spokesperson from British Transport Police said: "There was concern for the welfare of a woman near to Middleton.
"The call came in at around 1.30pm.
"Officers attended and the female was removed from harms way and taken to safety.
"The issue has been resolved now and the tracks should reopen shortly."
