A rescue official said that dozens of workers were trapped and efforts were going to retrieve them.
Twelve bodies of workers killed in the incident have been recovered while 74 injured have been rescued from the rubble, the Geo news reported.
The building in Sunder Industrial Estate area of the city was used to manufacture shopping bags and expansion work was going on the building when it caved in.
The injured labourers have been shifted to hospitals where they are being given emergency medical treatment.
The cause of mishap was not known but the structure had developed faults during the massive 7.5-magnitude earthquake that shook Pakistan last month.
