Firefighters helped to evacuate around 200 people from four floors and a basement of a building on Lowndes Street in Westminster after a smell of gas was reported. The building included offices, shops and residential properties.
Gas engineers found a gas main had been fractured and residents were advised to find temporary accommodation until the incident was resolved.
The Brigade were called at 1210 and the incident was resolved at 1628. Fire crews from Chelsea, Clapham, Paddington and Soho attended the scene.