A third knife attack at a kindergarten in eastern China's Jiangsu province has left three children in critical condition and 25 students injured. Most of the victims are only 4 years old. The police have detained Xu Yuyuan, 47, an unemployed man who has been implicated in an illegal pyramid scheme in the most recent of a spate of knife attacks on school children. On Wednesday, another knife-wielding man, thought to be an unhinged teacher from a competing school, injured 16 children at a primary school in Leizhou city. The Leizhou attack came on the same day that a third man, Zheng Minsheng, was executed for stabbing eight children to death and seriously wounding five others at a school in the Fujian province in March.