Rail traffic in Glasgow Queen Street was interrupted after a train hit a person at the eastern end.
ScotRail confirmed that the incident had forced the closure of the line between Carntyne and High Street
The operator said that it affects all trains via Glasgow Queen St Low Level and is expected to last until 17:00.
Services from Helensburgh Central / Milngavie to Edinburgh, Balloch, Airdrie, Dumbarton Central and Springburn are affected.
Anyone traveling from the west of the city to Glasgow will be asked to use the services via Glasgow Central Low Level.
An update to ScotRail's official Twitter account said, "Due to the magnitude of the disruption, we are currently unable to leave Helensburgh, Balloch, Dumbarton Central or Milngavie services.
"We work closely with the rescue services and will provide more information on train traffic as soon as possible.
"Services on our Argyle Line (via Glasgow Central Low Level) will be delayed."
Customers can use tickets and smartcards for First Glasgow buses between Glasgow and Airdrie and for services from Glasgow to Cumbernauld / Falkirk Grahamston via Stepps.