Four fire engines and two fire rescue units were called to a flood caused by a burst water main on Lea Bridge Road in Hackey, E5.
An underground car park was completely flooded and local homes and commercial properties were affected.
Firefighters used inflatable boats to rescue several people from affected buildings, including three adults, a child and a baby.
Firefighters used pumps to remove water, and Thames Water and officers from the Metropolitan Police Service were on the scene.
Thames Water worked to fix the problem, and 30 million litres of water was diverted into the nearby canal.
Station Manager Jason Frisby, who was at the scene, said: "Firefighters worked hard to reduce the impact of the burst water main on local homes and commercial properties.
"We worked with Thames Water and the Environment Agency to divert the clean water into the nearby River Lea and asked people to avoid Lea Bridge Road and the surrounding area.
"This was an extensive flood. Fortunately we are well equipped to deal with flooding but it is certainly quite unusual for firefighters to have to rescue people with inflatable boats in the capital."
Around 40 firefighters from Homerton, Stoke Newington, Bethnal Green and Euston are at the scene.
The Brigade was called at 0849 and the incident was over for firefighters at 1910.