Rescuers had pulled out 55 people from the rubble of the four-storeyed under construction building, which collapsed Tuesday evening at Kumareshwaranagar in the heart of Dharwad, about 400 km from Bengaluru.
"Seven people have lost their lives," Director General of Police (chief of fire and emergency services) M N Reddi told PTI.
Earlier, Hubballi-Dharwad commissioner of police M N Nagaraj said 55 people had been rescued.
He expressed apprehension that about 15 to 20 people were trapped inside the rubble.
No arrests have been made, Nagaraj said.
"We have registered a case. Arrests will also follow but our focus at present is on the rescue operations," he added.
Police said rescue operations had been intensified to extricate 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 engaged, two from Ghaziabad and one from Bengaluru.
"Two more teams of #NDRF are being airlifted from Ghaziabad in addition to one team which was moved from Bangalore in connection with Dharwad building collapse," the NDRF tweeted earlier in the day.
About 150 police, fire and emergency personnel too have joined the rescue operations.
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.
Most of those trapped were migrant labourers from north India who were engaged in laying tiles.
'Seven people have lost their lives,' Director General of Police (chief of fire and emergency services) M N Reddi told PTI.