No additional details were given about the attacker.
Parents rushed to the school after the attack, and the building and grounds were subsequently cleared.
Zheng Minsheng, a former doctor, was executed on Wednesday for a March 23 attack in which he killed eight children in the city of Nanping, in Fuijan, a province adjoining Guangdong.
Zheng apparently carried out the murders while he was depressed after being jilted by a girlfriend.
Many couples in China have only one child due to a law to regulate population growth.