(CNN) -- At least two people have died and up to 40 people are feared trapped after a roof collapsed at a construction site in eastern South Africa, emergency services say.
The collapse occurred in the township of Tongaat, near Durban.
Thirty people have been transported to the hospital with injuries ranging from moderate to critical, Crisis Medical operations director Neil Powell told CNN from the scene.
Powell said the construction work had been taking place beside a shopping mall.
40 feared trapped in building collapse
"It's unknown exactly what caused the collapse. There was a large amount of scaffolding and cement foundation that collapsed on to some of the construction workers," Powell said.
He said the rescue operation was taking place "with a lot of difficulty" as darkness fell.
"A local crane has arrived to start clearing the rubble to look for unaccounted people," he said.
"We're waiting at this stage to get to the rubble that is still crushing an estimated 30 to 40 people."
The South African Press Association reported that a 100-meter area of 18-inch-thick concrete slabs had collapsed late Tuesday afternoon local time.
Sapa reported that the the collapsed building was a shopping mall under construction.