© HandoutWitnesses said the attacker appeared to have mental health problems.
Two of the youngsters suffered "relatively serious" injuries, according to a report by state broadcaster CCTV.
The incident happened at a school in the city of Beilu in the Guangxi Zhuang autonomous region, the report said, adding that police had detained a suspect and were investigating the cause of the attack.
The Jimu News website identified the attacker as a 25-year-old man and quoted witnesses as saying he appeared to have mental health problems.
© HandoutTwo of the children suffered "relatively serious" injuries, according to China's state broadcaster CCTV.
When the public realised what was happening, a group of people armed with sticks encircled the attacker to stop him from escaping while they waited for the police to arrive, the report said.
Images shared online showed children bleeding from their wounds and being taken to hospital for treatment.
Others showed members of the public queuing up to donate blood in response to an appeal sent out by the local authorities.
A few such reports we carried on Sott during a particularly brutal cluster of attacks in 2010:
8 school children stabbed to death by doctor in China
A middle-aged man has stabbed eight children to death and injured at least five others at a primary school in south-eastern China. The suspect attacked the children with a knife at the gate to a...Chinese city goes on defense after school attack
A Chinese city shaken by one of three back-to-back attacks on schools stepped up security and urged its citizens to "trust the government" Saturday, a day after parents of the injured children...China: Man Hacked 7 Children and 2 Adults in Latest Attack at School
An attacker with a cleaver hacked to death seven children and two adults at a kindergarten in northwest China on Wednesday, the latest in a string of savage assaults on the country's schools....