More than 70 firefighters have been dealing with a blaze at an industrial bakery unit in Tottenham.
London Fire Brigade said the building in West Mews had collapsed. Four people had to be led to safety from a nearby smoke-filled property.
The brigade said nobody was injured during the fire, which was brought under control just after 01:00 BST.
At one stage crews were using jets to protect a 2,000-litre diesel fuel tank. The cause of the blaze is not known.
London Fire Brigade said it was called at around 18:20 BST to the incident. Ten engines and 72 firefighters and officers were at the scene.
From there station manager Charles Hanks said: "Crews were confronted with a large fire when they arrived and are now working hard to confine it to the bakery and stop it from spreading to any neighbouring factory units.
"There is some fuel stored on site but crews have isolated the supply and it is not involved in the fire."
Firefighters remain at the scene investigating the blaze and damping down.