Police arrested a 50-year-old Kailua High School teacher for allegedly throwing a hammer at a student, who had to have four stitches on his head.

David Izumi, who lives in Kailua, was arrested Wednesday and cited for third degree assault, a misdemeanor. He posted $200 bail.

Police said the hammer hit the boy on the head.

Following the incident, the Department of Education placed the teacher on leave and the matter is under investigation.

The teenager and his parents reported the incident on April 14, police said.