A "meltdown" at Clapham Junction causing chaos on routes into London and leaving thousands of passengers stranded on trains will continue into the evening rush hour, spurring Network Rail to advise Londoners to leave work early or late to avoid disruption.
A Network Rail director also warned that there is still likely to be delays tomorrow morning, speaking to the BBC.
A power supply failure between Clapham and Wandsworth Common has caused major disruption to commuters travelling to and from the capital on Southern and Gatwick Express services.
Emergency services, including police, fire and ambulance, had to evacuate passengers from one train which was stranded for five hours and thousands have been affected after the problem hit during peak rush hour this morning.
What's happening right now?
National Rail is advising passengers to check the latest updates from rail operators before they travel and to leave work earlier or later to avoid rail disruption.
"Passengers can use London Underground, London Bus, London Tramlink, South West Trains, Southeastern and Thameslink services to complete their journey. If possible, passengers are advised to consider starting their journeys either earlier or later than normal for a better journey home.”
As of 4.45pm here's how the commute's looking.
“At Victoria station the entrance onto Buckingham Palace Road may be closed and the whole of the station is likely to be very busy with a queuing system in place for services on platforms 15-19. Other platforms will be busier than usual," said Network Rail.
Southern/ Victoria station
There's a very limited service running into and out of Victoria. Southern is advising passengers to avoid the station completely and find other routes.
Main Line East/Victoria station
Victoria to Eastbourne/Ore services will start and terminate at Haywards Heath. Customers can use Thameslink services to Haywards Heath.
Main Line West/Victoria station
Victoria to Littlehampton services will start from Haywards Heath. Customers can use Thameslink services to Haywards Heath.
Victoria to Portsmouth Harbour/Littlehampton will start from Gatwick Airport or Three Bridges. Customers for Havant can use South West services.
Gatwick Express/Victoria station
There are no Gatwick Express services currently running from Victoria Station.
The problems have had a knock-on effect on London Bridge, which has advised that a one-way system is in place.
A one-way system is in place due to severe service disruption. Please check your journey and consider alternatives.— London Bridge (@NetworkRailLBG) April 30, 2015
Southern services through Clapham running to and from London Bridge are severely delayed.
Thameslink services through London Bridge are subject to delays and alterations at short notice.
Southeastern services are unaffected, but "resulting congestion may impact Southeastern passengers" the train company said, advising to allow additional time for journeys.
At Clapham Junction, South West trains are running into Waterloo, however, infrequent Southern trains are making some platforms busy.