Students and staff at a high school in north-west NSW have been offered counselling after a "large bone" was excavated on the grounds.
Police have set up a crime scene at St Mary's College in Gunnedah, about an hour's drive west of Tamworth, after the remains were found soon after 9am.
NSW Police has confirmed the remains have been recovered and will be forensically tested to determine if they're human.
Specialist police officers were sent to the scene from Tamworth to assist with investigations.
A statement from the Catholic Schools Office of the Armidale Diocese said the "large bone" had been "unearthed during routine maintenance".
"While the bone has not [yet] been identified as human, it is routine in such circumstances for NSW Police to investigate the scene and make a determination," the statement said.
The said additional counselling resources have been put in place for students, parents and staff at the school "who may be distressed by the news".
"The wellbeing of all our staff and students continues to be our priority."