Passengers at London St Pancras have been warned of delays and cancellations throughout the afternoon.
The rail route between St Pancras and Luton has been disrupted today after all lines were closed shortly before 1pm.
A person was hit by a train and the emergency services are attending, National Rail said.
Major disruption is likely to continue at least until 5pm, impacting East Midlands Railway and Thameslink services, although EMR said disruption could last until the end of the day.
Services could be axed, delayed by up to 60 minutes or revised.
Travel advice for commuters
Passengers travelling on Thameslink services to Bedfordshire and Northamptonshire are advised to delay their journey until later today if possible.
Trains in both directions between West Hampstead Thameslink, St Albans City, Luton and Bedford are unable to run for the time being, National Rail warned.
Journeys using replacement services and changes are likely to take an hour longer than usual.
Meanwhile, rail replacement has been requested, but places are limited and wait times could be high.
East Midlands Railway (EMR) passengers are advised to use other stations to get to their destination.
Journeys to Sheffield can be completed via a change in Doncaster with CrossCountry, TransPennine Express or Northern.
Derby and Chesterfield can be reached by travelling to Birmingham New Street with CrossCountry and then catching a train to London Euston with LNR or Avanti.
Nottingham-bound passengers are advised to head to Grantham with EMR before changing for a London King’s Cross train.
Leicester can be reached from St Pancras by heading to Nuneaton on CrossCountry and changing for a London Euston Avanti or London Northwestern Railway train.
All of the alternative travel options are available in both directions, and train operators are aware of the disruption, National Rail announced.
Get in touch with our news team by emailing us at webnews@metro.co.uk.
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