Six fire engines and around 40 firefighters were called to a burst water main in Offord Road in Islington.
A number of properties were affected by flood water and crews distributed sandbags to help prevent water from entering further properties.
Local road closures are in place on Caledonian Road between the junctions of Wheelwright Street and Copenhagen Street.
The Brigade was called at 0622 and the incident was over for firefighters at 0928. Fire crews from Islington, Euston, Shoreditch, Soho and other surrounding fire stations attended the scene.