Cars and gardens in Muswell Hill were left under eight inches of water after a water main burst.
A spokesman for the London Fire Brigade said fire fighters had been called just after 2.30pm, and that the flood had seeped into eight basement properties.
"We're pumping water away using sandbags to prevent the water from going further and working with water companies to get the main isolated," he said.
At 4.49pm, Thames Water tweeted: "We are aware of a burst pipe on Muswell Hill Road. We are sending engineers to investigate ASAP."
A video posted by Twitter user Amy Clayton showed firefighters wading through the water on Muswell Hill Road, with cars stranded in the flood.
Other social media users also posted images of the water:
Muswell hill road completely under water pic.twitter.com/7rnkVPvdyZ— Muswell Hill Media (@muswellhm) October 10, 2016
Jeff Overs tweeted this image, in which it seems the dog is far more enthusiastic about the new water feature than its owner.