The incident affected LNER, Cross Country and Transpennine Express services on the East Coast line.
LNER said: “A man has been hit by a train between York and Darlington. All lines are currently closed to allow emergency services to deal with the incident safely.
“Trains running between these stations may be canceled or revised.
“Severe disruptions are expected until the end of the day.
“If you’ve been hurt by what happened online today, there’s always someone to talk to. You can contact the Samaritans on 116 123 from any phone for a confidential chat.’
The LNER has advised that the buses replacing the rail should operate as follows:
2 York Pullman buses will run between York and Northallerton
2 York Pullman buses will run between York and Darlington
“Customers who wish to postpone their journey tonight and travel tomorrow, Monday 20 February, can do so using their original tickets,” it added.