South Africa's Gauteng Province Premier Panyaza Lesufi told reporters as he visited the scene on Wednesday that investigations were under way to determine what type of gas was involved.
"Sixteen is the verified number. The team has assured me that they have done a recount," Lesufi said.
The previously reported number of deaths was 24.
The bodies were scattered over the area, Lesufi said, adding that the youngest victim was a one-year old.
"It's not a nice scene at all, it's not a nice scene. It's painful, emotionally draining and tragic," the premier said.
Broadcaster SABC earlier quoted a spokesperson for the disaster and emergency management services as saying there were 24 deaths.
South African media reported that the gas leak could have been linked to suspected illegal mining activities.
