Beijing, China (CNN) -- A man with a kitchen cleaver hacked to death seven kindergarten students and a teacher in northwest China on Wednesday, before returning home and committing suicide, state media 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.
The Wednesday morning incident left five boys, two girls and a female teacher dead, said the Xinhua news agency.
In addition, 11 children and an adult 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 weeks.
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 four-year-olds. Police arrested a 47-year-old suspect. The incident happened in Taixing city in Jiangsu province.
And 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 April 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.
See a timeline of school attacks in China
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.
