A gas leak at the Angelo settlement near Johannesburg on Wednesday left 16 people dead, including children.
William Ntladi, the spokesperson for the emergency services told the AFP news agency, "We have confirmed 16 deaths at the scene. However, paramedics were able to revive several others who were then transported to the hospital."
Ntladi added that among those hospitalized, four are in critical condition, while eleven remain in a serious but stable condition. One minor was fully conscious.
A higher earlier death toll was revised downward after some victims were resuscitated.
Initially reported as a gas explosion, emergency services later discovered upon arrival that the problem was a gas leak from a cylinder containing a toxic gas.
What caused the leak
Panyaza Lesufi, the Gauteng province premier, tweeted videos from a shack where at least four gas cyclinders can be seen on metal stands. The video also shows what Lesufi said was the cylinder responsible for the leak lying on the floor next to the entrance of the shack.
Ntladi said, "The cause of the incident is alleged to be a nitrate oxide gas leakage from a cylinder used in an illegal mining activity in and around the settlement. Apparently, the illegal miners used the gas to extract gold from the soil."
When they reached the scene, near the middle-class suburb of Boksburg, rescue workers and forensic police encountered numerous individuals lying unconscious after inhaling toxic gas.
Angelo consists of shabby brick and corrugated iron sheet shacks and is at the base of an old, abandoned mine.
South Africa, which has an unemployment rate exceeding 32%, has a significant number of illegal miners known as "zama zamas" (meaning "those who try their luck" in Zulu). These unregistered miners risk their lives scavenging for gold in defunct mines in harsh and hazardous conditions.
Johannesburg, the country's commercial hub, and its surrounding regions are characterized by towering mounds of soil and deep pits left behind by mining operations that began during an 1880s gold rush.
Boksburg, the same suburb where the recent gas leak occurred, experienced a 5.0 magnitude earthquake last month. The tremor was suspected to be linked to the extensive network of underground tunnels and shafts associated with illegal mining in the area.
The suburb previously witnessed a gas tanker explosion on Christmas Eve last year, claiming the lives of 41 individuals. A truck transporting liquefied petroleum gas (LPG) got trapped under a bridge, leading to a leak and subsequent blast.
Multiple individuals, including patients and staff members at a nearby hospital, sustained severe burns from the explosion, which also caused extensive damage to infrastructure.