SUTHERLAND police were called to Jannali High School after a student, 14, was allegedly assaulted this morning.
Police said the school went into lock-down after a boy, 14, was assaulted by a 17-year-old who does not attend the school.
Inspector Rod Rae said the school would have done this to try and keep the offender on the grounds.
Paramedics were called to the school on Sutherland Road to treat the boy who allegedly suffered from bruising and swelling.
Police received a call about 11.50am and several cars responded.
Inspector Rae said reports of a firearm being used were not true.