The line into and out of Nottingham between Nottingham and Beeston has been closed and emergency services are currently on the scene.
In statement on its website, East Midlands Railways said: “We are sad to report a person has been hit by a train.
“This has occurred between Nottingham and Beeston and is disrupting our trains on most of our routes.
“At present the emergency services are on site and Network Rail also have a team en-route to manage the incident.
“Trains running through the area in both directions cannot run between Nottingham and Beeston.”
It said it expects its advertised timetable to resume on the affected routes by 5pm.
EMR said: “As soon as the line is open again, our priority will be to get trains running to their advertised times again.
“You should continue to travel as originally planned however your journey will be delayed significantly.
“We are sorry for the delay to your journey today.”
For the latest updates, visit the EMR website here or its Twitter feed at @EastMidRailway.