Firefighters were called to Euston Railway Station after an overhead power cable snapped on to the roof of a train car just outside the station.
Crews worked with partners to move around 400 passengers on board the train to the platform safely. There were no reports of any injuries.
The Brigade was called at 0932 and the incident was over for firefighters by 1317. Three fire engines and a fire rescue unit from Euston and Soho fire stations attended the scene.