All trains to London from Manchester have been suspended due to a signalling fault at Euston station.
The problem has left thousands of travellers stranded around the country.
Network Rail says it expects the issue to last until at least 8pm tonight.
Manchester Piccadilly tweeted that all Virgin Trains services to London are now suspended and advised that tickets are being accepted by Northern and Transpennine Express to London via Leeds.
Travellers are being advised to talk to staff for assistance.
Several took to social media to describe the chaos at the station.
Steve Taylor tweeted: "Carnage at Manchester Piccadilly again @VirginTrains All London trains suspended so people getting off the trains; whilst you announce the trains are going, so people running onto the trains"
A statement on National Rail website reads: "All lines are blocked at London Euston due to a fault with the signalling system at this station.
"This is causing major disruption and trains may be cancelled, delayed by up to 60 minutes or revised.
"Disruption is expected until 20.00"
The London Euston twitter account tweeted that engineers "are working hard to get this problem fixed."
Passengers are advised to keep checking National Rail for the latest.
