Families have been searching mortuaries in the South African city of Johannesburg a day after one of the worst building fires in the country’s history.

At least 76 people were killed in the blaze, including 12 children.

Panic-stricken and desperate, Grif, a Malawian who would only give his first name, arrived at the Diepkloof morgue.

There, among the dozens of bodies, many burnt beyond recognition, he found one of his two missing younger sisters.

The 26-year-old got a call in the early hours of Thursday morning about the fire, and he immediately started going to different hospitals in the city to look for Miriam and Fatima. After a few hours, it became clear, he needed to change his search.

On Friday, he began looking in the city’s morgues and eventually went to Dieplkloof in the Johannesburg township of Soweto, where all the victims had been brought.

Standing outside the low-rise building, teary-eyed and exhausted, he told the BBC that he was able to identify one of his sisters.

Lucky may not be the right work in this instance, but the authorities say that only 12 out of the more than 70 bodies are identifiable by sight.

Grif said he would keep searching for his other missing sister.

The two women lived together in the condemned and over-crowded five-storey building in central Johannesburg. Grif lived in a similar one nearby.

Many of the victims are thought to be undocumented migrants, eking out a living on the margins of South African society.

“I’m feeling so much pain,” Grif said. “And I’m scared to tell my family. It’s too painful and there’s nothing I can do.”

Earlier in the day, firefighters had gone back inside the building to see if they could find any more bodies.

Johannesburg Fire Service at the fire site

The cause of the fire is still unknown, but forensic investigators have also been at the site, picking through the charred remains of the burnt-out structure.

The government has promised help to all the victims, but it is a very difficult situation for many of them, as they are in the country without official papers. Some fear that coming forward could expose them to the authorities.

Twenty Malawians are thought to be among the dead, according to that country’s foreign ministry, quoted by the Reuters news agency.

Tanzania’s Acting High Commissioner Peter Shija has said that he has so far found out that five of his compatriots died in the blaze and three were injured. He told South African news broadcaster eNCA that 150 Tanzanians had been living in the building before it was engulfed in flames.

Visiting the scene in central Johannesburg on Thursday evening, President Cyril Ramaphosa called the tragedy a “wake-up call for us to begin to address the situation of housing in the inner city”.

The building used to be a home for abused women and children, but once the lease expired, it was “hijacked”, President Ramaphosa explained to reporters.

Many properties around the area where the blaze happened have been deemed unfit to live in.

Yet these old blocks, abandoned by their owners or the city authorities, are full of families, often paying rent to criminal gangs who run them.

Some of those who use the buildings include undocumented migrants, mostly from other African countries.

The conditions inside many of them resemble shanty towns, with flimsy partitions separating homes, and little or no access to running water and power.

Some reports suggest that a candle, paraffin stove or faulty electricity connection may have been behind Thursday’s blaze.

The country is just emerging from winter, with night-time temperatures in Johannesburg this week dropping to 4C.