Passengers who stayed on a broken down train while others forced open the doors after it stopped were locked on board by transport police.
The First Capital Connect Service to Cambridge from King’s Cross, stopped outside Foxton, near Cambridge, shortly before 1700 BST on Friday.
About 15 people broke open the doors and walked along the track to the station, which was just yards away.
The remaining passengers were locked on board for several hours.
At about 2200 BST the train was towed back to Royston in Hertfordshire from where buses took people back to Foxton and Cambridge.
A spokesman for First Capital Connect said problems with overhead power cables had halted the train, which also called at stops in Hertfordshire.
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