An unemployed man entered a kindergarten in Jiangsu province in eastern China on Thursday morning and stabbed 28 kindergarten students and three adults, critically wounding at least five children, local authorities and state news agencies reported. It was the second mass stabbing of students in two days, and the third in less than a month. Many of the wounded children were just 4 years old and shared the same classroom, according to the state-run Xinhua news agency. Police officers identified the assailant as Xu Yuyuan, a 47-year-old former insurance agent. According to Xinhua, he began attacking children with a knife about 8 inches long around 9 a.m. at the Zhongxin Kindergarten, a middle-class school in Taixing, about 570 miles southeast of Beijing. He also wounded two teachers and a security guard. Little other information was immediately available. Taixing propaganda officials did not respond to telephone calls. Thursday's attack occurred a day after a 33-year-old man in the southern province of Guangdong stabbed 15 fourth- and fifth-graders at a primary school in Leizhou. None of those students was seriously wounded. The authorities said that attacker, identified as Chen Kangbing, had taught at a nearby school but had been on leave since 2006, apparently because of mental illness. On March 23, Zheng Minsheng, 42, stabbed eight primary school students to death in Fujian province, also on China's east coast. Some news reports stated that Zheng also had mental problems, but most state media said no such evidence existed. Mental illness remains a closeted topic in modern China, and neither medication nor modern psychiatric treatment is widely used. An analysis of mental health issues in four Chinese provinces, published in June in the British medical journal The Lancet, estimated that 91 percent of the 173 million Chinese adults that are believed to suffer mental problems never receive professional help. Zheng's attack stirred calls for a school safety crackdown. Zheng was executed on Wednesday after what one legal expert, He Weifang, a former Peking University law professor and civil rights advocate, said was an unusually speedy trial. Some experts like He said that beyond mental illness, rising strains in China's fast-changing society might have a role in the growing number of violent crimes. Most school assaults have occurred on the east coast, where both the cost of living and income inequality are high. The man executed on Wednesday, Zheng, wanted revenge on 'rich' and 'powerful officials' in Nanping, where he lived, Xinhua said, quoting his neighbors. 