LONDON -- More than 50 people were killed in a fire that engulfed a five-story building in central Johannesburg early Thursday, authorities said.

The blaze broke out in the downtown area of South Africa's largest city at around 1:30 a.m. local time. Firefighters were dispatched to the scene and began evacuating people from the building while trying to extinguish the flames, according to Robert Mulaudzi, spokesperson for the City of Johannesburg Emergency Management Services.

At least 52 people were confirmed dead on scene, Mulaudzi said, while 43 others were treated for injuries and later transported to various hospitals for further medical care.

"At this stage, the cause of the fire incident is still a subject of investigations," Mulaudzi said in a statement. "Officials from City of Johannesburg Disaster Management have been activated to start facilitating relief for affected families."

This is a developing story. Please check back for updates.