Demonstrators are blocking motorways in South African in protest at the murder of white farmers.
People have been posting their pictures on Instagram:
The BBC's Pumza Fihlani in Johannesburg says the protests are already causing racial divisions after some demonstrators were seen carrying the flag from the apartheid era, when South Africa was governed by its white minority and black people were not allowed to vote.
Arts and Culture Minister Nathi Mthethwa took to Twitter to express his disapproval.
We strongly condemn the racism on display at the #BlackMonday protest with the brandishing of the apartheid flag. This is unacceptable.— Min. Nathi Mthethwa (@NathiMthethwaSA) October 30, 2017
The protest comes three days after two white farmers were sentenced to more than 10 years in prison each for forcing a black man into a coffin. They intend to appeal against the sentence.
Those behind the protests have urged people to wear black:
While most photos appear to show only white protestors, some show a racial mix:
The protest was organised to show outrage at the killings of farmers, especially after the death of a white farmer in Klapmuts near Stellenbosch.
Last Tuesday, Joubert Conradie, 47, was shot on his farm and died later at the Stellenbosch Mediclinic.
What are the stats?
The idea that white farmers are being targeted has been going around for some time. The fact-checking site Africa Check found back in 2013 that white people in South Africa are less likely to be murdered than any other racial group.
The spokesman for the priority crime police unit, known as the Hawks, Brigadier Hangwani Mlaudzi told the BBC's Milton Nkosi that the police did not keep specific statistics about farm killings.
"Cases are not classified as farm murders. They form part of all murders under investigation," he said.