Members of the British Transport Police (BTP) along with paramedics were called to the incident at about 4.05pm this evening (Monday, October 17).
A spokesman for BTP said a man was pronounced dead at the scene. His family have been informed.
“A file will be prepared for the coroner,” the spokesman added.
“The incident is not being treated as suspicious.”
Delays of up to an hour are being reported between Gatwick Airport and Brighton/Lewes due to the incident.
Southern Rail tweeted to say the line has now reopened, but residual delays are expected to last until 8pm and Wivelsfield station will remain closed.
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