Seven workers have been confirmed dead. Authorities in the city of George on South Africa's south coast released new information on the injuries, saying 16 of the 29 people rescued from the debris were in a critical condition in hospitals and six others had life-threatening injuries.
They said 39 workers were still unaccounted for and buried in the rubble of concrete and mangled metal scaffolding.
The collapse of the building that was under construction sparked a desperate rescue effort that has seen specialist disaster response teams brought in from other towns and cities to help.
A total of 75 construction workers were at the building site when it came down, the George municipality said.
More than 200 rescue personnel continued to search for survivors using sniffer dogs and underground cameras.
Cranes and other heavy lifting equipment were brought in to lift some of the huge concrete slabs that came crashing down on workers, while rescuers formed lines to remove the smaller rubble by hand.
Rescuers said some of the survivors had used their cell phones while trapped under the debris to contact family members and that had helped emergency responders find them.
There were cheers and applause when some survivors were brought out Tuesday night.
The George municipality continued to call for donations of water, energy drinks and food for the rescue personnel, who had been working in shifts for more than 40 hours.
The provincial Western Cape government has sent emergency response teams from Cape Town and other cities to help with a rescue effort that officials said would likely last at least until Friday.
George is a city of around 150,000 people on South Africa's picturesque coastal Garden Route and is renowned as a vacation and golfing destination.
Authorities have announced multiple investigations into the cause of the building collapse, including by police, the provincial government and the national department of labor.