The issue, which has been resolved, is causing major disruption at one of London’s busiest stations.
A signal points failure at London’s Euston station caused all lines to shut, prompting major travel disruption.
The issue has been resolved after it was first reported at about 10:40 BST, according to National Rail.
The operator has said passengers can expect delays of up to 90 minutes and cancellations, while major disruption is likely to last until 15:30 BST.
A Network Rail spokesperson apologised to customers.
They said in a statement: “We’re sorry for the disruption to services in and out of London Euston earlier today while our engineers repaired a fault with the signalling system in the area.”
Avanti West Coast and London Northwestern Railway said tickets impacted by the disruption would be valid on some other train services.
Ticket acceptance has also been agreed with East Midlands Railway and Thameslink between Bedford and Wellingborough to assist passengers travelling to or from London St Pancras International.
BBC journalist Alex Smith, who is at the station, said: “I’ve spoken to some staff who say that they don’t know what trains are turning up between platforms one and seven, and where they are going to – resulting in numerous, last-minute dashes for trains as they get announced.
“It is absolute chaos.”
Analysis
By Alex Smith, BBC News
I had a ticket for a London Northwestern Railway service from London Euston to Coventry, which was cancelled.
With no services to Coventry or nearby in sight, I – along with dozens of others – rushed to an Avanti train, the platform of which was announced suddenly and without warning, that stopped in Rugby, as I was advised I could use some Avanti services due to the cancellations.
However, from there I still had to get a train to Coventry, but my priority was getting out of London.
The train from Euston was temporarily stopped from leaving as there were too many people on the train, meaning it was too unsafe to travel until some “volunteers” got off the train. I have since arrived in Coventry.
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