Johannesburg - Fifteen people were arrested outside Hoërskool Overvaal on Thursday for public violence and contravention of the Explosives Act.
This comes after protesters threw a petrol bomb at a police van.
The group fled the scene but were soon arrested by police officers.
READ: 10 arrested for Hoërskool Overvaal protest
Police spokesperson Lieutenant Colonel Lungelo Dlamini said those arrested face charges of public violence and contravention of the Explosives Act.
They are expected to appear in the Vereeniging Magistrate's Court on Friday.
Protesters, mostly clad in ANC and Congress of South African Students (Cosas) T-shirts, gathered outside Hoërskool Overvaal in Vereeniging on Thursday.
'Kill the boer, kill the farmer'
They held placards that read: "Away with racism. Sebono SA Maburu [boers' ass]".
Some were heard chanting: "Kill the boer, kill the farmer".
Protesters also barricaded the roads leading to the school with burning tyres and rocks.
Emotions ran high after police requested protesters to remove their vehicles that were blocking the roads.
"The white people blocked the R59 on Black Monday and you [police] did nothing. We will not remove our cars," one of the protesters told police.
A delegation from the South African Human Rights Commission (SAHRC) met with school officials, police and demonstrators at the school, calling on all parties to act with restraint and ensure their actions were peaceful.
"The commission is heartened by the fact that the demonstration did not disrupt classes at the school, however, it did note the concerns raised by some parents about the safety of their children," said SAHRC spokesperson Gail Smith.
'I call on all boere to come in masses'
School officials apparently assured they would prioritise the safety of pupils.
In light of the petrol bombing, the commission was concerned about the impact of escalating tensions and strongly condemned any violence.
"The commission will continue to closely monitor developments at Hoërskool Overvaal," said Commissioner André Gaum.
"However, there is a clear need for broader discussions on the transformation of the public education system, including on the issue of language policies at schools at the level of both basic and higher education. The commission intends to play a central role in this regard."
On Wednesday, a voice note started circulating, calling on all "boere" to go in their masses to protect children at the school.
"I call on all boere to come in masses together on 18 January 2018 to High School Overvaal," the woman, speaking in Afrikaans, said.
"I give instructions that we must protest in peace and that we will not stand for any enemy that tries to disadvantage our children, schools and language.
"Come let us demonstrate together as a people - we can stand in unity. Our children, schools and language are no one's punching bag."
READ: 'I call on all boere to come in their masses to Hoërskool Overvaal' - voice note goes viral as protesters gather
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