Another 43 were injured, some suffering from smoke inhalation, and were taken for treatment at local hospitals, Emergency Management Services spokesman Robert Mulaudzi said.
“The death toll is at 64…(including) seven children,” Mulaudzi said, with some left burned beyond recognition.
The youngest victim was less than two years old, he said.
Firefighters at the scene had put out the flames and search and recovery operations were ongoing.
“We are moving floor by floor conducting these body recoveries,” Mulaudzi told local broadcaster ENCA.
An AFP reporter at the scene said emergency services were continuing to bring charred bodies out of the building, laying them down under blankets and sheets on the street outside.
“It is indeed a sad day for the city of Johannesburg… over 20 years in the service, I’ve never come across something like this,” Mulaudzi said.
It was not immediately clear what caused the blaze, which broke out overnight.
Mgcini Tshwaku, a member of the city’s mayoral committee in charge of public safety, said candles used for lighting inside the structure were a likely cause.
– Security gate closed –
The building, which has been evacuated, is located in a deprived area of what used to be the business district of South Africa’s economic hub, and was used as an informal settlement, Mulaudzi said.
“A lot of people” might have been trapped inside when the fire started, he added, suggesting many in the building may have been squatting illegally.
“Inside the building itself there was a (security) gate which was closed so people couldn’t get out,” said Tshwaku.
“Many burned bodies were found stashed at that gate.”
Fire trucks and ambulances were parked outside the red and white building with burned-out windows, which has been cordoned off by police, as a small crowd of onlookers gathered in the area.
Illegal occupation of disused buildings in the city centre is widespread, with many said to be under the control of criminal syndicates who collect rent from occupants.
In June a blaze ripped through a dilapidated building in Johannesburg and killed two children under ten who were locked in an apartment.
AFP