At least 17 people have died from nitrate gas inhalation following a gas leak at an informal settlement camp in South Africa. Officials say the leak came from a gas cylinder at the informal settlement. An initial investigation indicates the leak could be linked to illegal mining activity in the area. Illegal mining, mostly for gold, has remained rife in South Africa and costs the country millions of dollars each year. Known as “zama zamas,” they make up thousands of illegal miners who swarm the disused gold mines of Johannesburg. Last month, the country’s Department of Mineral and Energy Resources said around 31 suspected illegal miners who were believed to be nationals of neighbouring Lesotho had died in a ventilation shaft in the country’s Free State province.