Spokesperson Adele Myburgh said the boys, aged 9 and 12, were playing in the street with three other boys when they were approached by a man known to them who was driving a donkey cart.
"He asked the boys to assist him to fetch food for his pigs," she said.
All five boys climbed on the donkey cart and were then taken to an open field at Ipelegeng.
The man then instructed a 12-year-old boy to rape his eight-year-old friend.
After the incident, the man then raped the 12-year-old boy.
Myburgh said the other three boys aged 8, 9 and 10 witnessed the incident.
The man was arrested on Monday.
He remained in custody and was expected to re-appear in court soon.