Lines into Leeds station are blocked and services severely disrupted due to a “trespasser on the railway”.
Network Rail said overhead electric wires had been switched off while police officers dealt with the situation.
A spokesperson for Network Rail said “all lines are currently blocked and trains may be cancelled, delayed or revised”.
Disruption is expected to last until at least 12:00 BST.
- Latest live updates on the disruption
Passengers are being turned away by staff unless their journeys are “absolutely necessary” and are being advised to leave the station.
Yorkshire Ambulance’s Hazardous Area Response Team is also at the scene along with an incident response unit.
Train operators Northern and London North Eastern (LNER) are using buses to replace some of the cancelled services.
LNER said eight coaches would be operating between Leeds, York and Doncaster.
The incident has caused disruption in other places with most train services at York railway station currently delayed.
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