A nighttime fire ripped through a rundown five-story building in Johannesburg that was occupied by homeless people and squatters, leaving at least 73 people dead early Thursday, emergency services in South Africa's biggest city said.

Some of the people living in a maze of shacks and other makeshift structures inside the derelict building threw themselves out of windows to escape the fire and might have died then, a local government official said.

A witness said he saw people throwing babies out of the burning building in an attempt to save them and that at least one man died when he jumped from a window on the third floor and hit the concrete sidewalk “head first.”

As many as 200 people may have been living in the building, witnesses said, including in the basement, which should have been used as a parking garage. Others estimated an even higher number of occupants.

The youngest a 1-year-old

Seven of the victims were children, the youngest a 1-year-old, according to an emergency services spokesperson.

City officials said 141 families were affected by the tragedy but could not say exactly how many people were in the building when the fire started. Many of the people inside were foreign nationals, the officials said.

Emergency crews expected to find more victims as they worked their way through the building, a process slowed by the conditions inside. Dozens of bodies were lined up on a nearby side road, some in body bags, and others covered with silver sheets and blankets.

Another 55 people were injured in the blaze, which broke out at about 1 a.m. in the heart of Johannesburg's central business district, Johannesburg Emergency Services Management spokesman Robert Mulaudzi said.

- This is a tragedy for Johannesburg. Over 20 years in the service, I’ve never come across something like this - Mulaudzi said.

 Africa’s richest city

A woman who asked not to be identified said she lived in the building and escaped the flames with her grown son and a 2-year-old child. She stood outside holding the toddler for hours and said she didn’t know what happened to two other children from her family.

“I just saw smoke everywhere and I just ran out with this baby only,” the woman said. “I don’t have any home, and I don’t know what to do anymore.”

Johannesburg is rated as Africa’s richest city but its center is rundown and often neglected. Abandoned and broken-down buildings are common, and people desperate for some form of accommodation often take them over. City authorities refer to the structures as “hijacked buildings."

The building in question was reportedly owned by the city of Johannesburg and is considered a heritage site but not regulated by the local government.

It was the site of South Africa’s notorious “pass” office, which controlled the movement of Black people under the racist system of apartheid, according to a blue historical plaque hanging at the entrance.

“Denied a place in the city, many were ordered to leave Johannesburg,” the plaque reads.

Decades later, the deadly fire made the building an emblem of the exclusion of poor people in Johannesburg,

Speaking at the scene, Gauteng province's police commissioner, Lt. Gen. Elias Mawela said police were aware of approximately 700 buildings in central Johannesburg that were derelict and abandoned by their official owners. He urged city authorities to act.

More bodies inside the building

Mulaudzi, the emergency services spokesperson, said the death toll was likely to increase and more bodies were probably trapped inside the building. The fire took three hours to contain, he said, and firefighters needed time to work through all five floors.

The building's interior was effectively “an informal settlement” where shacks and other structures had been thrown up and people were crammed into rooms, he said. There were “obstructions” everywhere that would have made it very difficult for residents to escape the deadly blaze and which hindered emergency crews trying to work through the site, according to Mulaudzi.

Search teams found 73 bodies. The chance of anyone else being found alive hours after the fire broke out was “very slim,” he said.

Another witness who didn't give his name told television news channel eNCA that he lived in a building next door and heard people screaming for help and shouting “We're dying in here” when the fire started.

Mgcini Tshwaku, a local government official, said there were indications that people lit candles and fires inside the building for light and to keep warm in the winter cold. Officials were looking into the cause of the blaze but Tshwaku said the initial evidence suggested it started with a candle.

As the fire raged, some occupants got trapped behind locked gates at the exits, Tshwaku said, and it was clear there was no proper fire escape routes.

“People couldn’t get out,” he said.

After the fire was extinguished, smoke still seeped out of windows of the blackened building as daylight broke. Sheets, blankets and other items that had been twisted into makeshift ropes hung out of some of the broken windows.