Gallo
The alleged perpetrators had been on the run since last Sunday, Warrant Officer Kay Makhubela said.
One of them, also aged 17, was taken to a place of safety.
The arrest came a week after a mentally ill girl was gang raped by seven men also in Soweto.
Makhubela said police suspect the boy was drugged.
"After the rape the boy told his granny what happened and she immediately came to police," he said.
Makhubela said this rape was similar to three other unresolved cases which involved women drugging and raping men.
The Young Communist League of SA said it was disgusted by the crime.
"We demand the arm of the law to deal harshly with these criminals," spokesman Mangaliso Khonza said in a statement.
"This gruesome behaviour that is on the increase poses questions [about] our society and as communities we have to start creating forums for speaking and curbing this behaviou..."
