No one was reported hurt or killed in the mishap, they said.
The blaze occurred at a slum establishment on S L Raheja road in Mahim. About half-a-dozen hutments came in contact with the flames, a fire control room official said.
The control room got a call at around 11 AM about the blaze following which five fire tenders were immediately rushed to the site, he said.
Efforts were on to douse the flames, he said adding that the cause of the fire was yet to be ascertained.