CNN  — 

At least nine students were killed and nearly a dozen injured in a knife attack Friday evening at a middle school in Shaanxi province, China, according to the state-run Xinhua news agency.

A male suspect was arrested by police, and an investigation is ongoing, Xinhua reported, citing local government officials. The victims included seven female and two male students.

Knife attacks at schools in China are common. Last year, a man climbed over the wall of a kindergarten and attacked 11 students. None suffered life-threatening injuries.

In 2016, a man in the southern province of Hainan stabbed 10 children before killing himself, authorities said. And another man killed three students at a school in 2014 before jumping off a building.

Perhaps the worst spate of stabbings occurred in 2010, when attackers targeted schools on three consecutive days. China’s Ministry of Education responded by ordering schools to beef up security and to bar strangers from campuses.

China also began requiring people to register with the government when buying large knives.

CNN’s Steven Jiang and Joshua Berlinger contributed to this report.