About 30 people were evacuated from their homes in north London after a burst water main left some areas under around 40cm of water on Sunday night and Monday morning.
The London Fire Brigade said 10 fire engines and around 70 firefighters were responding to the incident in Islington, which was expected to be “protracted”.
The public is being urged to avoid the area around Canonbury Street, Essex Road, Elmore Street, Halliford Street and Ecclesbourne Road and to avoid driving through flood water.
Emergency services received more than 23 calls about the incident shortly after 10pm on Sunday night, the brigade said.
Fire crews from Islington, Holloway, Stoke Newington and Euston were at the scene alongside representatives from Thames Water, Islington Council and the Metropolitan Police.
A spokesperson for the LFB said on Sunday night: “Ten fire engines and around 70 firefighters are dealing with flooding in the area around Canonbury Street in Islington.
“A 36-inch burst water main has caused flooding up to a depth of around 40cm of water. This has affected properties on Canonbury Street, Essex Road, Elmore Street, Halliford Street and Ecclesbourne Road.
“Around 30 residents have been evacuated from their homes as crews work alongside Thames Water, the local council, and the Metropolitan Police Service to support affected people and make the scene safe.
“This is expected to be a protracted incident, with disruption likely to continue into the morning. The public are being urged to avoid the area and not to attempt to drive through flood water.”
A spokesperson for Thames Water said: “We’re aware of a burst water main on Essex Road – Canonbury Street, N1, and our engineers are already on site investigating.”