Firefighters were on stand-by after reports of a gas leak in Chapel Market in Islington.
Met Police cordoned off an area of 25 metres. Around 150 people have been evacuated and road closures were in place. Firefighters capped the gas main and left it in the care of the gas authority.
The Brigade was called at 0910 and the incident was over for firefighters at 1205. Two fire engines from Islington and Euston are at the scene.