A man travelling on the Gatwick Express bound for London was killed after he leant out of the window and was hit by an oncoming train.
Emergency services, including an air ambulance, were sent to the scene, at Wandsworth Common station, south west London, at about 5.45pm on Sunday.
The man, believed to be in his 20s, was pronounced dead at the scene, after receiving what police described as ‘serious head injuries’.
A British Transport Police statement said: "Our investigation remains at an early stage, but initial enquiries suggest the man may have been leaning out of a train door window when he suffered a blow to the head.
"Officers are currently working to confirm his identity and inform his next of kin.
"The death is not being treated as suspicious and a file will be prepared for the coroner."
