BEIJING (AP) — Authorities say a man with a kitchen knife has attacked first- and second-graders at a school in central China, injuring eight children.

The government of Macheng city in Hubei province said the man was detained following Tuesday’s attack. It said on its website that police are investigating the motive.

The statement said the injured students are being treated at a hospital.

China has suffered a series of attacks on kindergartens and grade schools, often by people who are mentally ill or are angry at society. Education officials have ordered tighter security at schools throughout the country.