A 15-year-old boy in Perth, Western Australia, has been sentenced to three years in juvenile detention for carrying out Australia's first school shooting.

The incident, where the teenager fired three shots with two rifles at Atlantis Beach Baptist College, resulted in no injuries as staff and students took cover.

The boy had undiagnosed autism spectrum disorder, was suffering from depression, and obtained the firearms from his father's gun cabinet.

He had researched school shootings online and discussed his plans on social media prior to the incident.

The judge imposed a three-year sentence due to the incident's severity, with a minimum of 16 months before parole eligibility, but expressed hope for rehabilitation.