The building was precariously “sitting” on the first floor, trapping the two labourers in the basement, one from Karnataka and another from Kolkata, police said.
Rescue operations were on to bring out the trapped, police said.
Eight persons sustained injuries including two seriously but it wasn’t life-threatening, police said.
The six-storey building was being built in a crowded locality cheek by jowl with neighbouring structures and it was found that the owner had violated norms, constructing additional floors.
Transport Minister B Ramalinga Reddy, who is also in-charge of Bangalore Urban district, blamed engineers of Bruhat Bangalore Mahanagara Palike for dereliction of duty, in addition owner and builder for usage of sub-standard material for construction. Suspension orders would be issued against BBMP engineers found responsible for the lapse.