Thousands of commuters have been left stranded at train stations on their way to work after wiring problems at Hendon cancelled a large number of services.
Damage to overhead wiring at Hendon Overground station has caused services between Luton and London St Pancras on the Thameslink line to be cancelled.
The disruption is also severely affecting services from Borehamwood.
First Capital Connect says there will be no trains running until the damage to the wires has been assessed.
The problem is also affecting a number of South Eastern Rail services.
Many customers have taken to Twitter to express thier frustration this morning.
Alex Nunn wrote: "Took my husband three hours to get to work today after getting stuck at Elstree for over 30 minutes with no news."
First Capital Connect is now running replacement bus services between stations.
For live updates and information, keep checking www.firstcapitalconnect.co.uk.