A man has been killed after leaning out of a train window and being hit by another train, according to reports.
The passenger who was travelling on a Gatwick Express train was pronounced dead at Wandsworth Common station, south west London on Sunday evening.
London Ambulance Service said they were called to the station at 5:34pm.
"We sent an ambulance crew, a single responder and a car and an incident response officer to the scene alongside an air ambulance," a spokeswoman said.
"We treated a person at the scene for a head injury but sadly they were pronounced dead by the doctor from the air ambulance."
A spokesman for Gatwick Express said it first received reports about the incident on board one of its trains which was en route to Victoria from Gatwick at 5.45pm.
He said: "The emergency services are in attendance at Wandsworth Common station. We have no further information at this stage.
A spokesman for British Transport Police said the incident was not being treated as suspicious, and a file is being prepared for the coroner.
Southern Rail, which runs Gatwick Express, said over Twitter that rail services between Victoria and Balham were delayed.
The Tweet said: "Emergency services dealing with an incident between Balham & Wandsworth Common."
Additional reporting by Press Association
