Trains have been brought to a halt at Durham as officers speak to a man on the tracks.
British Transport Police were called to the railway near Durham at around 3.40pm on Thursday to concern for the welfare of a man who had trespassed onto the line.
All lines between Durham and Darlington were blocked as a result until the man was brought back to safety.
A spokesperson for the British Transport Police said: "Officers were called to Durham station at 3.40pm following concern for the welfare of a man.
"Emergency services remain on scene and are currently working to bring the man to a place of a safety."
All lines reopened just after 5pm.
Disruption is expected on CrossCountry, LNER and TransPennine Express trains until around 6.45pm.
Trains may be cancelled or delayed by up to an hour.
Passengers on CrossCountry are able to use their ticket on TransPennine Express services between York and Newcastle.
Anyone who experiences a delay of 30 minutes or more can claim compensation from their train service.
