Eight persons trapped in the debris of the six-storey under-construction apartment building, owned by SP leader Mehtaab Aalam, were also rescued, the police official said.
Deputy Inspector General of Police Rajesh Modak confirmed the number of deaths and informed that many of the injured were still in critical condition.
Most of the victims were labourers and their families from Chhattisgarh. The incident occurred on Wednesday afternoon when the sixth floor was being constructed.
All of a sudden, the building crumbled like a pack of cards and thereafter there was chaos and wails for help, an eyewitness told IANS.
All through the night, the National Disaster Response Force teams, who were rushed in from Varanasi and Lucknow, continued their relief and rescue operations.
The Army was also helping, a district official informed. But since the building is located in a narrow lane, rescue work was hampered.