Four fire engines and 21 firefighters and officers were called to reports of a gas leak in St Martin's Lane, Covent Garden.
Approximately 100 people were evacuated by the Brigade as a precaution.
Local road closures were in place.
The Brigade was called at 1015 and two fire engines will remain at the scene standing by. Fire crews from Soho, North Kensington and Euston fire stations attended the scene.