There were 20 people on board the bus, Xinhua, the official government news agency, said. The survivors were all injured, including a 3-month-old baby girl who was in critical condition, a spokesman for the local government said.
The crash occurred around 6 a.m. in the Guangxi Zhuang autonomous region, as the bus traveled from Nanning to Dahua.
Wei Yuegang, the mother of the injured girl, said she and other relatives were on their way to a wedding. She said passengers were thrown from the minibus as it fell.
"Passengers who were still conscious shouted for help. Nearby villagers came and saved us," she said.
Officials said eight people died immediately, another while being transported to a hospital and one other after arrival.