JOHANNESBURG (AP) — 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.

Seven of the victims were children, the youngest a one-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.

A woman who asked not to be identified said she lived in the building and escaped the flames with her grown son and a two-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 centre 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, Lieutenant General 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.