Fourteen fire tenders and 10 water tankers were pressed into service to douse the fire, he said.
The official said a portion of the building, where the fire broke out, collapsed after three blasts.
"Our control room received a call at 1.20 am about flames emanating from the second and third floors of the ground-plus-three building," the official said. Eight people were rescued from the building, he said.
The official said the building is a commercial-cum-residential property partly made of wood.
Three blasts, possibly triggered by LPG cylinders, resulted in a portion of the building caving in, the officer said.
The structure is located in a congested area of south Mumbai and the fire fighting team faced difficulties in reaching the spot and dousing the flames, the official said.
The cause of the fire is yet to be ascertained, he added.
The incident is the latest in a spate of fire mishaps reported in the financial capital in the last four months.
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