National Rail reported a person has been hit by a train between Retford and Newark North Gate, blocking all lines between the stations.
It said trains between Doncaster and Grantham may be delayed by up to 60 minutes.
There is currently no estimate for when the line will reopen but disruption is expected to continue until approximately 11am.
Services being affected include:
Grand Central between Bradford Interchange and London Kings Cross.
Hull Trains between Hull and London Kings Cross.
Virgin Trains East Coast between Harrogate, York, Edinburgh, Leeds and Glasgow Central.