Sniffer dogs were repeatedly sent during the night over the football pitch sized portion that had collapsed on Tuesday afternoon.
Members of the police's search and rescue units conducted an audio test early on Wednesday morning, tapping and knocking at numerous places in the wreckage in the hope of hearing a reaction from trapped workers.
The test did not elicit any response.
When the disaster unfolded on Tuesday night initial reports were that as many as 50 people had been entrapped. Netcare 911 spokesperson Chris Botha said that one person, a woman, had died and 29 people had been taken to hospital.
It was still unclear how many workers had been on the construction site and how many were unaccounted for. A train passing by in the early hours of the morning had commuters leaning out of windows and doors to see what was happening.
Many were using their cell phones to film or photograph the devastation.
Construction worker Skhumbuzo Ngcobo said that all he saw was dust when the slab collapsed.
"Next thing all of us were down on the floor with the scaffolding and everything. I hurt my hand, my back," he said from a hospital bed on Tuesday night.
'Going too fast'
He was three floors up on scaffolding setting up bricks for a bricklayer to use when a slab caved in. He heard one of his friends calling and he helped to pull him from the rubble onto the railway line.
They were not sure what else would collapse.
"The only thing I could see was concrete rubble and they were taking people from under the concrete. Most of them, I thought they were dead, because that place was finished," he said.
Ngcobo worked for a sub-contractor. He had been told that four people from his company, which he did not want to name, were still missing.
Asked what he thought had caused the accident, the 24-year old said construction on the mall had been going too fast to allow the concrete to set.
"That job, they doing it [too fast] and rushing it. They wanted to do a quick job [to] finish that thing. That's the thing I think went wrong."
He said that within two or three days of concrete being cast, scaffolding was being removed.
"I don't think that concrete was hard enough. They were building more walls on top of the slab, the top slab."
Earlier, eThekwini deputy mayor Nomvuzo Shabalala said construction at the mall should not have been taking place.
"We took them [the contractors] to court a month ago. We thought they had stopped," she said.
The municipality had approached the court because the contractors had not "followed processes".
Ethekwini Democratic Alliance councillor Brian Jaganathan said plans for the mall's construction started in 2010, when several people were forced to move from their homes to make way for the development.
"I found out that in 2010 no plans had been passed. In 2012 they started building and during the last month they were working at a high pace."
He questioned why the building had been allowed to continue despite the court order.
Lubabalo Ntanze, whose legs were injured, said he was laying bricks when the scaffolding underneath him gave way.
"I thought I was going to be dying when that wall came down," he said, also from hospital.
Fiona Moonean said she was washing dishes when the slab collapsed, directly over the railway line from her home.
A few days earlier, workers had started removing the scaffolding supporting the level, she said.
"Just after 16:30 it was a thunderous sound. Before the bang, I heard too much scaffolding fall. That's when I picked my eyes up [and looked through her window at the mall].
"The whole concrete slab crashed down with the pillars. The smoke and dust was too thick. I heard them screaming out for help in Zulu."