Mainline commuter services into London Euston were suspended this morning after a fatality on the tracks near Watford Junction.
Lines were blocked as emergency services responded to the scene, meaning mainline trains could not run, but they have since reopened.
In its latest update, National Rail said disruption is expected until at least 8pm and that as service recovers, trains may still be severely delayed by up to an hour or revised.
The incident has been affecting passengers travelling with Avanti West Coast, London Northwestern Railway and Southern.
