Two Katlehong primary school pupils died after complaining about serious stomach cramps, and their five-year-old brother, who had similar symptoms, is critically ill but stable in hospital.
Now Gauteng Education MEC Panyaza Lesufi has appointed an independent team to establish the cause of the deaths and to verify all available statements from the school and the parents.
Gauteng education department spokesperson Steve Mabona issued a statement in which he explained what transpired: "It is alleged that, while in the classroom, the Grade 4 [pupil] complained of experiencing stomach cramps and being nauseous.
"The [pupil] was taken to the local clinic. Subsequently, the Grade 1 [pupil] also complained of similar symptoms as the older sibling and was also rushed to the local clinic."
Complications set in and the Kumalo Primary School pupils - aged 7 and 10 - were certified dead on arrival at the clinic.
Later, when a teacher was sent to their home to break the news, the boys' brother was also found to be gravely ill.
The third child is receiving urgent medical attention at the Thelle Mogoerane Hospital while police investigate what happened.
READ: Sixth baby dies in Klebsiella outbreak
The same hospital is managing a crisis in which six babies have died as a result of a Klebsiella pneumonia outbreak.
The National Institute for Communicable Diseases says it has been investigating the outbreak for three weeks at the request of the provincial health department.
The Gauteng education department's psychosocial unit was also sent to the school and to the family to provide support.
"On behalf of the entire education fraternity in Gauteng, we would like to extend our deepest condolences to the family of the deceased [pupils] and wish them peace and comfort during this difficult time," said Lesufi.
"We hope that the family will find comfort in the knowledge that we too share their loss. No words are enough to express our sorrow at a loss of a child."
He intends to visit the children's family and the school on Wednesday.
KEEP UPDATED on the latest news by subscribing to our FREE newsletter.
- FOLLOW News24 on Twitter