By Alex Stambaugh, Dhruv Tikekar and Heather Chen, CNN
The death toll from a fire in a five-story building in central Johannesburg has risen to 63, according to the city's emergency services.
The number of people injured stands at 43, said spokesperson Robert Mulaudzi.
The fire has now been extinguished, rescue officials said, and emergency services are conducting recovery operations.
Videos taken moments after the fire broke out show huge orange flames engulfing the lower floor of a building and scores of people standing outside.
Speaking in a radio interview on Thursday morning, Mulaudzi said there were "hundreds" of informal settlements inside the building.
Photos taken on Thursday morning showed onlookers crowding around burnt out and cordoned off areas, broken glass windows, and clothes strewn around the building.
Johannesburg's emergency services confirmed that the fire had been reported at around 1:30 a.m. local time Thursday.
"At this stage the cause of the fire incident is still a subject of investigations," the statement read. "Officials from City of Johannesburg Disaster Management have been activated to start facilitating relief for affected families," it added.