Passengers on a northbound Tube train in south London on Friday broke windows and climbed out of the train following a fire alert. The incident occurred at Clapham Common station around 17:50 BST. British Transport Police confirmed that there were no reported injuries. Transport for London stated that the fire brigade attended the scene and confirmed that there was no fire. Sources said that the alert at the station was caused by a mechanical fault involving a ventilation fan on the train. TFL has launched an investigation into the incident and apologized for any distress caused at Clapham Common. London Fire Brigade reported that approximately 500 people had left the train before they arrived at the scene. They also stated that investigations were ongoing, but the report of smoke was believed to have been caused by the train's brakes.