Trains at Kensington Olympia have been suspended by the incident in Russell Gardens Mews since 4.20am today (June 17).
No trains are able to run between Shepherds Bush and Clapham Junction until further notice.
This is affecting Southern Railway services between Watford Junction and East Croydon, with trains being cancelled or terminated short.
National Rail has urged commuters to allow an extra 30 minutes to travel and find an alternative route.
A major disruption to train services has since been declared which is expected until the end of the day.
Officers are trying to speak to the man following concerns for his welfare.
If you need someone to talk to, Samaritans are available to contact any time day or night on 116 123.
A spokesperson for Metropolitan Police said: “Police were called at 04:21hrs to reports of a man on a roof in Russell Gardens Mews W14.
“He threw a number of items down onto nearby railway tracks.
“Officers are trying to speak to him following concerns for his welfare.â€
https://www.newsshopper.co.uk/news/24392459.kensington-olympia-london-police-incident-man-throwing-items/
