A person has been hit by a train.
The incident happened at St Albans City station near rush hour.
Emergency services have been seen outside the station.
Thameslink said services are disrupted between London St Pancras and Bedford.
Some lines have re-opened. Replacement buses are running between Radlett and St Albans.
Tickets are being accepted on Uno buses and on London buses and London Underground services.
The British Transport Police have been contacted.
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