British Transport Police were called to an area of track between Steeton and Silsden, near Keighley in West Yorkshire, at around 6am this morning.
Paramedics also attended but the person was pronounced dead at the scene.
Northern have said disruptions are expected to continue until at least noon, and warned passengers to expect delays and cancellations.
A British Transport Police spokesman said: "BTP officers attended the line close to Steeton and Silsden Railway Station on Saturday 1st February 2020 after a report that a PERSON had been struck by a train.
"Officers from BTP attended the incident, which was reported to police at 6.05am and is currently being treated as non-suspicious.
"Paramedics also attended but the person was pronounced dead at the scene.
"A file will be prepared for the coroner."
A statement on the Northern Rail website said: "All services between Skipton and Keighley, in both directions, are currently being suspended due to emergency services dealing with an incident at Steeton and Silsden.
"An estimate can not yet be given as to when normal services will resume.
"Road Transport will replace train services between Skipton and Keighley (B&N coaches, S-Line coaches, Phantom coach).
"Customers between Leeds and Keighley who are travelling to Carlisle or Lancaster/Morecambe, ticket acceptance is in place with Transpennine Express between Leeds and Manchester and Manchester to Lancaster/Carlisle."