BTP officers were called to Riddlesdown rail station in Purley on Friday, 22 March after a report that a woman and a child had been struck by a train.
The incident was reported to BTP at 8.29am and was also attended by Metropolitan Police officers.
Medics from the London Ambulance Service also attended, but a woman and a child were declared dead at the scene.
The station has been temporarily closed while officers and medics deal with the incident.
More top news
Police are appealing for help in tracing a family of six who are feared to be travelling to Syria.
A "truly despicable" thief stole from a woman while she suffered a violent epileptic seizure.
A senior health official has called for vitamin supplements for children amid warnings over a rickets 'epidemic'.