Passengers stranded on a train for more than three hours were led along railway tracks by police after a morning of chaos for commuters.
The 'controlled evacuation' followed damage to the electrified third rail between Clapham Junction and Wandsworth Common.
Thousands of commuters faced long delays during the busy morning rush hour.
Two trains ground to a halt in a deep cutting after being damaged by the third rail. One limped into the station, the other was evacuated.
George Hola tweeted:
Been on a train since 7 without any wifi controlled evacuation and now a walk to Clapham Junction.
A major power supply problem between Clapham and Wandsworth Common has disrupted Southern train services into London Victoria this morning. Engineers are on site and we aim to resume services as quickly as possible. Tickets are valid on all other routes into London and Southern passengers are advised to avoid travelling through Clapham Junction, which is very busy.