* 7 children and teacher die in kitchen cleaver attack at school in Hanzhong city
* Teacher's mother later dies of wounds in hospital
* Attacker returned home after attack and kills himself
* Latest attack follows others the last few weeks
Beijing, China (CNN) -- The death toll from an attack at a kindergarten in northwestern China rose to nine Wednesday after one of the wounded victims died, state media said.
A man with a kitchen cleaver hacked to death a teacher and seven kindergarten students -- five boys and two girls. He then returned home and committed suicide, state media said.
The teacher's mother, who was wounded in the attack, later died at a hospital -- bringing the toll to nine, the Xinhua news agency said.
Officials do not yet know what prompted the 48-year-old man to attack students at a private school in Shaanxi province.
It was at least the fourth such attack on school children in the last month.
See a timeline of school attacks in China
In addition to the fatalities, 11 children were wounded in the attack. Among them were two children who were hospitalized in serious condition, Xinhua said.
Twenty children attended the school.
China has seen a spate of attacks at schools in recent days.
On April 30, a man armed with a hammer injured five preschool children in east China before setting himself on fire in a classroom suicide, a government spokesman told Xinhua news agency.
The attacker held two children in his arms as he poured gasoline over himself, the spokesman said. Teachers in Weifang City, Shandong province, pulled the children away as the man died, the spokesman said.
On April 29, at least 28 children were injured when a man with a knife attacked a kindergarten in east China, state media said. Most of the victims were 4-year-olds and three of the children were in critical condition.
Police arrested a 47-year-old suspect. The incident happened in Taixing city in Jiangsu province.
On April 28, a man attacked 18 students and a teacher with a knife at a primary school in southern China's Guangdong province, Xinhua said.
The attacks come despite the execution of Zheng Minsheng, 42, a former community doctor who stabbed eight children to death and wounded five others at an elementary school in eastern China on March 23.
Zheng, executed by a firing squad in Nanping City late last month, told investigators he carried out the attack because he was frustrated by "failures in his romantic life and in society," according to Xinhua.
China Daily newspaper quoted Nanjing University sociology professor Zhu Li saying Zheng's attack inspired copycats.
"Some people may not have thought about stabbing school children, but due to the media's coverage of such a case, they got an idea," Zhu said.
Chinese authorities have begun teaching safety awareness in school curriculums, China Daily reported.
Officials also have tightened security in schools by hiring extra guards to escort students to and from class
This made me tear up. What the fuck is wrong with people? D: