It is understood that four other pupils from the same school also consumed poison recently.
They are, however, recovering at medical facilities.
A male general worker from the school has also allegedly committed suicide by consuming poison at home.
The South African Depression and Anxiety Group says it will be visiting Tsakane Secondary School this week following the suicide cases.
Gauteng Education MEC Matome Chiloane, through his spokesperson Xolani Mkhwemte, has expressed concern over this.
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Written by: Nokwazi Qumbisa