Trains between St Albans and Watford have been suspended following a broken down train on the Abbey Line.
Services between St Albans and Watford up to and including the 19.16 train have been suspended.
A replacement bus service is running, adding an estimated 30 minutes to journey times.
The problems began at around 2.00pm after a train travelling between the stations began to lose power.
A spokesperson from operator, London Midland, said that nobody appeared to be stuck on the train and services were expected to be up and running after 19.16.
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