A 15-year-old boy from Darwin has been charged with plotting a mass casualty terrorist attack, authorities announced Thursday. The teenager appeared in a Northern Territory youth court dressed in his private school uniform as he faced multiple charges.

Police allege the boy planned to target a school or place of worship. He has been charged with collecting documents with the intent to facilitate a terrorist act, possession of violent extremist material, and possession of firearms alongside materials for manufacturing explosives.

The arrest took place on Wednesday, during which officers reportedly seized 3D-printed gun blueprints and instructional documents connected to carrying out a terrorist attack. Additional material found in the teenager’s possession referenced previous violent attacks, according to police statements.

A judge reviewing the case described the allegations as “extremely serious,” underscoring the gravity of the charges. Details about the investigation, including potential motives or whether others were involved, have not been released. Authorities continue to examine the circumstances surrounding the case.