The roof of a South African mall under construction collapsed on Tuesday, leading to the deaths of two people, and an estimated 50 others still trapped beneath the rubble.

Rescue response teams arrived at the site of the mall in Tongaat township, located just north of Durban, Tuesday evening, and worked through the night clearing away the wreckage from the collapse. Crisis Medical told BBC that about 30 people had been taken to nearby hospitals for medical attention. According to officials working on the scene, those thought to still be caught below were construction workers.

"It was a mall building still under construction; most of those still trapped inside the building were construction workers," spokesperson for the police Mandy Govender told AFP.

Police and emergency services were called to the Tongaat mall site at about 4:30 p.m. local time, and were still working late that evening.

"Rescue operations are becoming extremely difficult in the dark," operations director for Crisis Medical Neil Powell told BBC.

Chris Botha, who works with private ambulance company Netcare 911, said that the cause of the collapse was still unknown, and it was far too early to tell.

"It is going to be a long operation, it will take time to get to everyone," he said.

About 100 rescue workers were at the mall using cranes to crush blocks of concrete as of Wednesday early morning. Photos from the site depicted people searching through piles of cracked, grey cement, bent spokes of twisted scaffolding protruding from the ground.

Tongaat is a small town whose local economy is primarily comprised of sugar cultivation, farming and sale.