An axe-wielding farmer in China attacked and killed six people on Wednesday morning, including two young students and four adults.

Thirty year old Wang Hongbin is said to have mental health problems, and may have suffered from schizophrenia. He has been detained by police, according to China Daily.

The attack happened outside of a kindergarten classroom in the city of Congyi in Henan province. According to a report, Wang rushed at two girls -- aged one and four years old -- and their parents as the children walked to school.

One of the girls and three of the adults were killed on the street, while the others died in a hospital from injuries sustained in the attack. Two others suffered minor injuries, China Daily reports.

Even before the killings, China had increased security at a number of elementary schools due to a wave of similar violence over the past year.

In August, eight children were injured when a female day-care employee slashed them with a box cutter. In 2010, 15 children were murdered and more than 80 wounded in five separate school attacks, including one in which a doctor stabbed eight children to death in Ninping.

A similar kindergarten axe attack occurred in May 2010, in the city of Hanzhong. Seven children and two adults died.

The attacks are possibly a frightening indication of the effects of rapid social change. Chinese Premier Wen Jiabao said last year that the killings were rooted in social conflicts and rising stress levels in China.

Most of the assailants were mentally unstable. A study published in Lancet in 2009 showed that around 17 percent of adults in China (173 million people) suffer from either permanent or temporary mental disorder, with a particular prevalence of schizophrenia.

Yet, despite the figures, very few seek or receive treatment, and outside critics are blaming the attacks on China's recent focus on economic growth and disregard for social problems.