According to investigating officer D.K. Palwankar of Kasa police station, near Dahanu town, the process of identifying the victims is underway and three men have been identified so far.
The DNA tests will be conducted to ascertain the identity of other victims before the bodies are handed over to their relatives, he said.
Among the dead are at least two women, while 24 injured people have been shifted to hospitals in Mumbai and Thane, Palwankar said.
The tanker was carrying around 35 tonnes of petrol when the driver lost control over it Saturday afternoon on the Mumbai-Ahmedabad national highway.
The tanker skidded, overturned, caught fire and exploded on the highway near Charoti village around 2.30 p.m.
Police officer Preeti Patil of Kasa police station said the burning, speeding tanker skidded down the highway, knocking down around 10 other vehicles in its path.
One restaurant and some small shops in the vicinity were damaged as leapt out from the tanker.
Teams of firefighters and police rushed to the site for rescue operations as massive traffic snarls blocked both sides of the highway near the Charoti toll post. One side of the highway could be cleared for traffic only by 6 p.m.
Eight injured people were admitted to hospitals.