British Transport Police said a person hit by a train on the Sussex to London line was a railway worker.
Rail services from Sussex to London were disrupted in the early hours of this morning (November 6) after the incident at Purley.
British Transport Police (BTP) confirmed a 37-year-old man from Upminster died at the scene.
DI Darren Gough said: “We’re at the early stages of our enquiries into this incident and at this stage we believe the man who died was very sadly a railway worker.
“We are doing all that we can to establish the circumstances behind what happened, and we have specialist officers supporting his family through this difficult time.”
BTP, London Ambulance Service and London Fire Brigade were called to the railway line just south of Purley at 12.30am, and rail replacement buses were put on between Redhill and East Croydon.
A BTP spokesperson confirmed a 37-year-old man from Upminster was pronounced dead at the scene, and said The Rail Accident Investigation Branch and the Office of Rail and Road (ORR) have been notified.
The incident affected Southern services between Redhill and East Croydon, which hasd an impact on trains travelling from London Bridge and London Victoria to Gatwick Airport, Brighton, Bognor Regis, Eastbourne, Littlehampton and Hastings, and Thameslink services between Bedford, Cambridge, and Peterborough to Gatwick Airport, Three Bridges, Brighton and Horsham.
At 4.28am this morning, Southern Rail said: “Trains are now able to run normally between Purley and Redhill, following the emergency services dealing with an incident involving a person being hit by a train.”