The blaze was first reported around 12:30 pm. 16 fire engines were rushed to the site in Damu Nagar area of Kandivali. The place is said to house a number of godowns. It took the fire engines nearly four hours to put out the blaze.
"We received a call at about 12.33 pm. Immediately, 16 fire engines, 12 water tankers and five fire brigade officials were rushed to the spot," a senior fire official said.
Video of the fire showed a plume of black smoke rising above a densely populated area.
A resident from a nearby area said he "heard a loud blast and then 20-30 explosions one after the other."
The slum is reportedly located in a congested colony, making it difficult for fire tenders to reach the site.
The fire has led to traffic jams in Kandivali.
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