According to Southern Rail, the person was hit by a train between Purley, Oxted and East Croydon.
As all lines are currently disrupted, trains across the whole Southern/Thameslink network will be cancelled or delayed – impacting many services connecting Sussex to London.
Major disruption to all Thameslink/Southern services which operate through East Croydon station is expected until 3pm.
Customers are being advised to travel later if possible.
Southern Rail said if you do travel now, your journey time will be extended by up to 60 minutes and will include an alternative route.