The 'Shakuntla' building, situated at Bazarpeth in Mumbra area of Thane district, collapsed after midnight when the residents were fast asleep, police said.
Police rushed to the site at around 2.30 AM and have launched relief and rescue operations.
The injured have been admitted to Kalsekar hospital, CSMH and Civil Hospital in the city, they said.
Thane District Collector P Velrasu, Police Commissioner K P Raghuvanshi and acting Municipal Commissioner Shaymsunder Patil rushed to the scene while a fire brigade team has also gone there for assistance.
On June 10, a four-storey building collapsed at Mahim in Central Mumbai in which ten people were killed and six injured.
Prior to this, a building crashed on April 4 at Shil-Phata near Mumbra in Thane district which claimed as many as 74 lives and left over 60 injured.
