A major blaze started in Camden Town's famous markets area at about 1920 GMT on Saturday, and about 100 firefighters went to the scene.
Thick palls of smoke hung over the area as police closed off several Camden streets.
Flames leapt up to 30ft in the air. Emergency services feared there might be gas canisters in the vicinity.
Eyewitness Nick Pomfret sent in this picture. He said of the fire: "It's absolutely huge, there's smoke everywhere and it looks quite scary."
Homeowners and revellers were evacuated from the area. Camden Town is a major tourist destination and attracts up to 300,000 visitors each weekend.
As the fire engulfed the market, its flames could be seen for miles around. Nina Schick sent in this photo taken from the roof of her home nearby.
With its vibrant mix of bars, clubs and restaurants, the area had been enjoying a normal Saturday night before the blaze broke out.
Firefighters struggling to bring the blaze under control battled it from three sides.
Theepan Saravanapavan, who took this photo, said he saw firefighters using an angle grinder to gain access to the shops beside The Hawley Arms pub in Camden.
London Fire Brigade said the blaze was being brought under control and there were no reports of casualties.