From the BBC, we read more about the attack.
"A convoy of returnees coming from the north to the south was ambushed... at about 1700 (1400 GMT) by armed Misseriya," Mr Chuang told reporters in the southern capital Juba.
"Ten were killed and 18 were wounded. The attackers came in six or seven vehicles with guns.
"Misseriya is not a foreign tribe. It is in Sudan and therefore is under control of the leadership in this part of the world. So the north is responsible," the minister added.
The convoy - made up of buses and trailers - was forced to turn back, south Sudanese officials said.
Thousands of people living in the north have been returning home to the south to take part in the landmark referendum.
Misseriya chief Hamid al-Ansari denied the group had been involved in the ambush.
Members of the nomadic cattle herding group were armed by the north during the 1983-2005 conflict.