A major incident has been declared at Kensington Olympia tube station following reports of a man on a roof throwing items onto the railway tracks.
National Rail said disruption is expected until the end of the day.
Overground trains have been suspended between Shepherd's Bush and Clapham Junction.
Southern trains between Watford Junction and Clapham Junction are also disrupted by the incident.
A major incident has been declared at Kensington Olympia tube station following reports of a man on a roof throwing items onto the railway tracksWiki Commons imagesTfL said in a statement: "No trains are able to run between Shepherds Bush and Clapham Junction until further notice.
"This will affect Southern services between Watford Junction and East Croydon, with trains being cancelled or terminated short.
"Please allow an extra 30 minutes to travel as you will have to use an alternative route.
"Check journey planners and station screens for the latest information."
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The incident has been ongoing since the early hours of this morning.
Officers said the man on a roof close to the track has thrown a number of items - which has caused lines to be blocked.
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 said the man on a roof close to the track has thrown a number of items - which has caused lines to be blocked
PAA sign outside the tube station reads: "There are no trains at the moment because of a trespass incident".
TfL added: "Tickets are being accepted on London Buses and London Underground services via any reasonable route."
A spokesperson for Metropolitan Police confirmed the incident is ongoing.
