Firefighters responded to a gas leak on Old Broad Street in the City of London.
There was a ruptured six-inch gas main at a six-storey office block. A 200-metre cordon was put in place and around 4700 people were evacuated from nearby buildings as a precaution.
Two fire engines and a Fire Rescue Unit from Dowgate, Shadwell and Bethnal Green fire stations attended the scene.
The Brigade was called at 1056 and the incident was over for crews by 1325, when responsibility for the scene was handed over to the local gas authority.