Santosh Kadam, in-charge of Thane Municipal Corporation's Disaster Control Room, said that two columns of 'Ahhsan Manzil' in Chandnagar near Bharat College sank this morning.
The four-storey building, constructed in 1992, has 35 tenements and 15 shops. The corporation had declared it as 'most dangerous' to live in.
However five to six families were still living there, the fire brigade sources said.
The building was later razed after evacuating the occupants.