An FIR has been registered against the contractor and the alleged owner of the building Samajwadi Party leader Mahtab Alam by the police.
Personnel of National Disaster Response Force, army, fire and emergency services are continuing operations.
According to sources, the personnel would take some time to conclude the rescue operations.
The incident took place when labourers were working on the sixth floor of the building. The cause of the incident was yet to be ascertained, but the officials said, as per preliminary report, substandard construction materials were used while constructing the building.
There are several multi-storeyed buildings, besides tannery units, in the nearby area.