Known as Janjawid, the militia raided the Abga Rajil village on Sunday 50km south of Nyala town, according to residents, some of whom were recovering in hospital from wounds sustained in the attack.
A senior Sudan Liberation Movement (SLM) member, Muhammad Mirsal, alleged that the attack took place after a meeting between President Umar al-Bashir and the Janjawid chiefs in the state.
Al-Bashir travelled to Nyala on Wednesday and said he was determined to resolve the Darfur conflict.
The conflict in Darfur, a region neighbouring Chad, started in February 2003.
Government troops and pro-government militias have faced off against the region's separatists.
The violence has killed 10,000, displaced one million people within Sudan and pushed 100,000 people into Chad, according to the UN - which calls it the world's worst current humanitarian crisis.
Both the rebels and the Khartoum government have accused one another of violating a ceasefire, while the government continues to manipulate access for aid workers and supplies to the region.