Rush hour railway passengers have been told to expect major delays due to a power failure.
Thameslink and East Midlands passengers have been advised to check before travelling after a blackout on Tuesday afternoon affected train services.
A spokesman for Network Rail, which runs the railways, said repair work is not expected to be completed before the Wednesday morning rush hour, affecting those travelling using Thameslink and East Midlands services into London.
He said: "Owing to a piece of cable coming into contact with the overhead wires at Luton station, there is currently a very limited train service through the area.
"We are working to repair the problem and get a full service running again as soon as possible, however this work is likely to continue into the morning peak.
"We apologise for the inconvenience this will cause and advise that passengers use an alternative route where possible and check with their train operator before they travel."
Rail passengers have been advised to check for updates on the East Midlands and Thameslink websites.