A person has been hit by a train between Manchester Piccadilly and Stockport, causing disruption to services in Chesterfield.
The incident is affecting trains on the Liverpool/Nottingham/Norwich route.
Normal service is expected to resume from 5.30pm, but people are being warned their train could be cancelled.
Network Rail and the British Transport Police are now on site and working to reopen the line.
A spokesman for East Midlands Trains said: “All of our trains will be diverted via Romiley, causing delays of up to 15 minutes.
“While the line is closed via Stockport, trains will not be able to call at the station.
“At present we are expecting the line to fully reopen in the next 60 minutes. A normal service is expected to run from 5.30pm
“If you are travelling between these stations your train may be delayed by 15 minutes on our diversionary route or cancelled.”
People can use their East Midlands Trains ticket on Northern and TransPennine Express services between Manchester and Liverpool.