"Three men died at the St George Hospital after they were admitted with severe burn injuries," a fire brigade official said, adding the injured person is recuperating.
The fire broke out at around 0920 hours in the basement of the Bombay House building, the headquarters of the Tata Group.
The cause of the fire and the extent of the damage is yet to be ascertained, the official said, adding the flames have been brought under control.
Image: Fire breaks out from the basement of Bombay House in South Mumbai on Wednesday morning
Photograph: Harshal Mantri