Queensland counter-terrorism police have charged a 13-year-old with planning an attack on a regional school north of Brisbane.

The teenager was arrested last Thursday after allegedly making threats at a business in Maryborough, armed with a knife.

Counter-terrorism police subsequently carried out a raid of his house and seized devices. Police allege they discovered evidence of a planned attack on devices seized at the house.

Acting Det Supt Jason Hindmarsh, from the counter-terrorism investigation group, said the 13-year-old was “quite well advanced” in plans to cause death and grievous bodily harm and posed an “imminent threat”.

“There was a threat to the school, and particularly our young people at that school,” he said.

Hindmarsh said the boy was not seeking to further any “ideological cause” and his devices were still being reviewed. His motivation is “one of our key lines of inquiry,” he said.

“It’s too early to say if there was an ideological, religious, or political motivation.”

Hindmarsh said police were investigating whether the boy was radicalised online.

“That’s part of our ongoing investigation as we analyse the devices,” he said.

The boy has been charged with 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.

The boy is also accused of attempting to enter premises with intent, going armed so as to cause fear, making threats and possessing a thing intended for use in connection with an offence.

He allegedly committed the latter offences at a business on Saltwater Creek Road, at about 9am on Thursday armed with a large knife.

“The actions of the youth on that day did involve a threat to a local school,” Hindmarsh said.

He said there was no ongoing threat to the community and support would be provided for the school community and the young alleged offender.

A spokesperson for the education department said guidance officer support was available for any students who may require it.

He was refused bail at Maryborough children’s court on Monday.