Experts at Sheffield City Council said a digger cutting through a load-bearing wall caused a three-storey building to collapse over the weekend.
Four people were trapped in the rubble and 20 left homeless after the first and second floor flats collapsed above a former curry house.
The council believe the collapse in Broad Lane, Brook Hill, was caused by digging machinery hitting the pillar.
A council spokesman told the BBC: “The building partially collapsed on Saturday when a mini-excavator being used by the shop fitters hit one of the internal load-bearing support columns.
“That meant that around 20 people, mainly students, living in the upstairs floors had to be evacuated.
The building above the former Butler’s Balti House was demolished completely on Sunday following the partial collapse.
An HSE spokeswoman said their investigation into the incident was likely to continue for “many months”.
Fire service incident commander Stuart Nicholson said: “We had crews on scene very quickly and they were faced with a huge hole in the middle of the three storey terraced building.
“The first and second floors had collapsed onto the ground floor.”
Source: Construction Enquirer
Lighthouse Comments: Planning is the most important part of any construction task. The fact that a digger operator hit one of the internal load bearing supports for the building may suggest that the operator was not competent. Basics again have been missed, where was the supervision for the task? It will be interesting to find out the full story, however this story highlights another failure in planning.