Two labourers were killed and seven others injured when an under-construction structure collapsed in Ghodbunder area in Thane on Friday, police said.
Prima facie, the digging operations underway at the site triggered the accident.
Regional Disaster Management Cell (RDMC) chief Santosh Kadam said some labourers could have been trapped under the debris.
Police PRO Sukhada Narkar said two bodies have been extricated so far from under the rubble, who are identified as Mohammad Abdul Hussain Lashkar (34) and Radhakant Barabhoye (32), both labourers.
A joint rescue operation is on at the spot by teams of Disaster Management cell, Fire brigade and police.