Braamfontein - A worker at the Braamfontein Office Park in central Johannesburg says she was on her lunch break when she noticed smoke coming from the roof.
Zanele Ngumbela, who works for Forum 4 at Braampark, said she was on a lunch break around 13:00 when she noticed four or five men on the roof.
"I don't know what they were doing, they were probably fixing the roof, but the next thing we saw was smoke," Ngumbela said.
The 28-year-old said the smoke first appeared as dust, but a few minutes later it became huge.
"At the time I made a joke about it, because I saw a blaze and I was like, 'the roof, the roof is on fire'. Little did I know, the roof was really on fire," she said.
She said they were thankful to God that no one got hurt.
Johannesburg Emergency Service spokesperson Synock Matobako said they were alerted to the fire around 13:45.
"It looks like the fire started on the fifth floor. When we arrived everybody evacuated the building," Matobako said.
The cause of the fire was not immediately clear.
Matobako said they will remain on the scene to monitor the situation.