Firefighters were called to reports of smoke coming from a train carriage at Marylebone Station on Friday evening.
The fire damaged an air conditioning unit beneath one of the train's six carriages and a small part of the carriage itself.
Station Manager Paul Hobbs who was at the scene said: “The fire affected one of the train’s carriages but crews worked quickly to put it out. Around 500 people were evacuated from the station's concourse before the Brigade arrived.”
As of 2355 on Friday crews were still at the scene and Melcombe Place near the station remained closed. Drivers were being advised to avoid the area if possible.
The Brigade was called at 2056 and the incident was over at 2333. Four fire engines, a fire rescue unit and around 25 firefighters from Paddington, Soho, Kensington and Euston fire stations attended the scene. The cause of the fire is under investigation.