According to Disaster Cell of the Thane Municipal Corporation (TMC), the fire broke out in one of the huts of Shanti Nagar slum colony situated on the Mafatlal Company open grounds on the eastern side of Kalwa, around 2.15 AM.
Soon the flames engulfed nearby dwellings and razed at least two dozen hutments while the occupants were deep asleep.
At least three fire engines and water tankers were rushed to the scene and the blaze was brought under control in about two hours, fire officials said.
The deceased was identified as one Suleman Shaikh (35). However, the number of injured is still unspecified.
The cause of the fire is still not known and a probe is on, officials said.