Limited details have emerged so far about what the boy's alleged plan was.
Initial reports by the ABC that St Helens State School was a target were inaccurate.
The teenager — who has been charged with one count each of preparation or planning to cause death or grievous bodily harm and possessing or controlling violent extremist material obtained or accessed using a carriage of service — remains in custody after appearing in the Hervey Bay Children's Court on Monday.
Queensland Police said the charges arose after the Counter Terrorism Investigation Group seized electronic devices from a Maryborough home on Saturday.
The teenager is due to reappear in the Hervey Bay Children's Court on Friday. (ABC Wide Bay: Grace Whiteside)
The teenager had been arrested two days earlier on May 28 after police were called to a BP service station on Saltwater Creek Road in Maryborough following reports of a person with a knife.
The boy was dealt with under the Youth Justice Act over one count of attempting to enter premises with intent, going armed to cause fear and making threats.
'Shocking allegations'
Fraser Coast mayor George Seymour said he was shocked to hear of the alleged offence in the regional community.
"There is nothing more important than the safety of children," he said.
George Seymour says the news is extremely concerning. (ABC Wide Bay: Lucy Loram)
"Maryborough and the Fraser Coast is a safe place where people feel safe and it is very concerning to see such a significant charge."
Health Minister Tim Nicholls said on Tuesday that he had "many questions regarding the shocking allegations".
"As is standard practice, Queensland Health is working with police as they conduct their investigations, including examining any interactions between the alleged perpetrator and the health system," he said.
The Department of Child Safety would not disclose whether the child was known to the department.
Speaking on Monday, Acting Detective Superintendent Jason Hindmarsh said it was too early to say if the boy had any ideological, religious or political motivations.
A bail application hearing is set down for Friday in the Hervey Bay Children's Court.
Editor's note 04/06/2026: This story has been updated to rectify earlier inaccurate reports that St Helens State School was a target.