WUHAN - A man allegedly upset about his daughter's rejected school registration killed three children and injured six others in a primary school Monday morning in central China's Hubei Province.

The knife-wielding man surnamed Chen later jumped to death from the school building at Dongfang Primary School in Yunxi County according to the information office of Shiyan City, which administers the county.

An initial probe suggests Chen held a grudge after his daughter was denied registration into the new semester's courses for not completing her summer vocation homework, police said.

At around 10:20 a.m., Chen stormed into a classroom and stabbed and injured nine people, including eight students and a teacher, before committing suicide. Three of the injured children later died. One student and the teacher were seriously injured, doctors said.

Monday marks the first day of new school year in most of Chinese schools.

It is not immediately known how Chen managed to enter the campus since security at schools was tightened following a spate of attacks on children in recent years, many perpetrated in schools and kindergartens.

In March 2010, a man killed eight children outside their elementary school in Fujian Province. Less than two months later, several separate attacks on children were reported across the country.

In the latest case in July, a cook killed a boy and injured two other children with a knife in a rented apartment in Guangdong Province.