Trespassers on the line are causing major delays to the rail network across South Yorkshire this evening.
East Midland Trains said people had gained access to the railway line at Sheffield and services through the city station are delayed by up to 30 minutes.
Services departing out of Doncaster are also affected.
A spokesperson for the rail company said: "Network Rail are currently on site along with the British Transport Police to apprehend the trespassers as soon as possible.
"We currently anticipate a normal service to resume from approximately 6.30pm."