Three teenagers, aged between 13 and 15, are expected to appear in the Johannesburg Magistrate's Court on Friday in connection with the murder of a Mondeor High School pupil.
Kulani Mathebula, 19, was on his way to school at around 07:00 on Wednesday when he was assaulted by three pupils, believed to be from a nearby school.
They face a charge of murder.
Shortly after the incident, police formed a team of detectives who followed up information obtained at the scene.
It led them to arresting the 13-year-old on Wednesday evening, who appeared in the Johannesburg Magistrate's Court's juvenile section on Thursday.
His case was postponed so that he could be assessed by a probation officer.
"The probation officer will then compile a report that will be presented to the court so that a process of conducting a preliminary inquiry can be kickstarted," said National Prosecuting Authority spokesperson Phindi Mjonondwane.
The 15-year-olds were arrested in Soweto and Naturena in the early hours of Thursday.
On Wednesday afternoon, pathology services removed Mathebula's body from a patch of grass, just 10 minutes away from his school. His school bag, blazer and shoes were next to his body.
"I want my son," his mother, Dumi Chauke, cried.
Gauteng Education MEC Panyaza Lesufi said his department would support the family and had offered them and other pupils counselling.
He said there had been many deaths at Gauteng schools in the first term.