The fire at the 23-storey government building in the CBD, which houses the Bank of Lisbon and the department of health, was still raging on Thursday morning and had spread to other parts.
The building caught alight Wednesday morning.
Johannesburg Emergency Services spokesperson Nana Radebe told 702 Talk Radio early Thursday morning that the fire had spread from the top floors to the 16th floor and that firefighters had left the building because the “water pressure was low”.
She said firefighting efforts would resume later in the morning.
Three firefighters lost their lives on Wednesday when the building caught alight. Several others have been hospitalised after suffering from smoke inhalation.