Trains stopped between Newcastle and Morpeth after a person was hit by a train.
British transport police officers and paramedics were summoned to an injured person on line at Cramlington station on Thursday at 3:00 pm.
It was confirmed that the person was declared dead on the scene.
A spokesman for the British transport police said: “The agents were called to Cramlington station today at 3:00 pm following news of an injured man on the track.
“Paramedics also attended, but one person was sadly declared dead on the scene.
“The agents are now working on identifying the person and informing their family.
“The incident was not treated as suspect and a file will be prepared for the coroner.”
Due to the emergency response, the trains were unable to run on this section of track.
Affected services include LNER, CrossCountry, Northern and TransPennine Express.
A replacement bus service is currently running between Newcastle and Edinburgh, as the break should last at least until 6pm.
Some trains have been canceled, including the 15.30 LNER train from Edinburgh to London Kings Cross, and other services are subject to delays of up to an hour.
LNER passengers can also use the TransPennine Express buses that will stop at Berwick.
Tickets for LNER services are also accepted by TransPennine Express and Avanti West Coast trains during closure.