Rescuers have so far pulled out 56 people from the debris of the four-storeyed under construction building, which collapsed Tuesday evening at Kumareshwaranagar in the heart of Dharwad, about 400 km from here.
Police said rescue operations have been intensified to extricate 30 people believed to be still trapped beneath the debris.
In addition to 10 ambulances and five fire tenders deployed for relief and rescue operations, three teams of the National Disaster Relief Force (NDRF) have been pressed into service, two from Ghaziabad and one from Bengaluru.
About 150 police, fire and emergency personnel too have joined the rescue operations.
No arrests have been made so far.
Former Karnataka minister and Congress leader from the region Vinay Kulkarni had said Tuesday that one of the partners in the building was his relative and that whoever was involved should face action.
An eye-witness had alleged that the building did not have the capacity to bear four storeys whereas an extra floor was being added.
"The builders had used substandard materials," he told reporters Tuesday.