A person has been struck by a train this afternoon, Monday April 16, meaning there are no trains running between Peterborough and Stevenage.
All lines are currently blocked following the incident at Sandy in Bedfordshire.
Virgin Trains tweeted: "Unfortunately we must advise a person has been struck by a train near #Sandy.
"All lines are currently blocked and trains may be delayed by up to 120 minutes whilst the emergency services do their work and deal with this tragedy."
Disruption is expected to continue until approximately 8pm.
British Transport Police added: "Officers were called to the station at approximately 3.20pm today (16/04) and attended alongside paramedics. They are now working to identify the person and inform their next of kin.
"Enquiries are underway to understand how the person came to be on the tracks."
A spokesperson added: "Network Rail and the train operators are working with the emergency services to reopen the railway lines as quickly as possible. Whilst this incident is ongoing, services may be delayed or subject to alteration.
"Shuttle train services are running between London Kings Cross and Biggleswade and also between St Neots and Peterborough.
"You may use your tickets on Greater Anglia services between London Liverpool Street and Peterborough."
If you or someone close to you has been affected by this incident or other,there is always someone to talk to.
You can contact the Samaritans on 116123 free at any time, on any phone.
The CALM Nationwide Helpline number is 0800 58 58 58, or 0808 802 58 58 in London. You can also visit www.thecalmzone.net for confidential Webchat.
More details to follow as we have them...