South African emergency workers say hopes are fading of finding survivors under a collapsed half-built mall near Durban as heavy machinery was called in to remove the rubble.
"The search was called off 30 minutes ago to allow city engineers to use heavy machinery to remove concrete," Neil Powell of private emergency firm Crisis Medical said on Wednesday.
Powell said the search could resume if signs of life were detected but that after nearly 19 hours into the search hope was fading.
"So far there has been no sign of life, it could be that there are not people there at all or they are trapped beneath the rubble. We don't know."
He said fibre optic cameras had not picked up any hint that survivors were still there.
One person has died and 29 people have been rescued after the vast roof of the structure collapsed on Tuesday afternoon in the town of Tongaat.
Chris Botha of private emergency medical firm Netcare 911 said 29 people "were treated and stabilised and they were taken to hospitals, one of them by helicopter."
A woman was found and died at the scene, while others were treated for broken bones, multiple fractures and crush injuries.
Under emergency lighting rescue workers toiled through the night with sniffer dogs and specialist equipment trying to find an unknown number of construction workers who may still be trapped.
Their effort has been hampered by a lack of information about how many people were working on the build.
Cheap labour means it is not unusual to see hundreds of workers toiling away at construction sites in South Africa and the incident occurred at 4.30 pm (0130 AEDT Wednesday), just as many labourers were knocking off.
Police spokesman Thulani Zwane said officers were trying to interview the contractors and owners to know how many people are missing.
There were earlier suggestions that the toll could be as high as 50. But rescue workers on the scene appear to have significantly revised down that estimate.
The site is vast, at around 200 metres long and in parts still unstable.
The incident happened around 40 kilometres north of the Indian Ocean city of Durban.
Fiona Moonean, who lives across from the building site, was washing dishes when she heard a "thunderous noise" coming from outside.
"There was this sound, it was too huge, that I picked my head up - at that point I just saw the whole slab - that just came down and all you could hear was the guys screaming," she said.
The cause of the roof collapse was not immediately clear, but police said they had launched an investigation into possible culpable homicide.
According to local government officials the construction company had been issued with a court order to stop work last month.
