Wingham High School went into lockdown on Thursday morning, August 15.
Shortly before 10am there was an incident involving a student and a staff member.
Manning Great Lakes Police were called to the scene.
According to the NSW Department of Education, students were kept in class as a precaution while staff and police resolved the matter, with nobody being hurt.
School resumed as normal at about 10.45am.
"Wingham High School does not tolerate any inappropriate behaviour and immediately takes appropriate disciplinary action," said a spokesperson from the Deparment of Education.