Thousand of commuters had journeys home delayed on Thursday night after a signal failure at Euston station.
Pictures shared on social media showed huge crowds gathered inside the central London station after services ground to a halt.
Problems were first reported at around 4pm and Network Rail warned passengers of "significant disruption" after all services out were stopped.
Lines were said to be reopened about an hour later but delays continued well beyond 9pm.
READ MORE: Commuters warned of all-day rail disruption after Glasgow to Edinburgh shutdown
Chris Dickinson, 25, from Burnley, said his journey from Manchester Piccadilly was delayed by nearly six hours.
"I'd like to say I was surprised, but I'm not, it seems like a flaw the railways have had for as long as I've used them regularly, and it's just a matter of time until something like it happens to you," he said.
He said passengers were told the delay was due to "overhead power line damage".
Network Rail also said crowd control measures were put into place during the disruption, after customers complained they were left waiting outside the station unable to get in.
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