Two teenage boys have been charged after allegedly planning a potentially deadly and "catastrophic" massacre involving explosives at a school in country South Australia.
Police will allege the duo intended to cause harm to "a large number of people" at the high school in the state's Riverland region.
More National News Videos
Teens arrested before alleged school massacre
Police have arrested two teenagers who were allegedly plotting an attack on a Riverland school in South Australia.
Searches allegedly discovered knives, and homemade body-armour and bombs.
It is believed the teenagers were planning an attack involving explosives and knives at the school between June 1 and November 7 this year.
![Detective Superintendent Des Bray.](http://web.archive.org./web/20171129202529im_/https://www.fairfaxstatic.com.au/content/dam/images/g/z/v/7/g/7/image.related.articleLeadwide.620x349.gzv67i.png/1511955789967.jpg)
One boy, 16, has been charged with solicit to murder while the other, 18, has been charged with four counts of aggravated threats.
It is believed one of the boys charged was a student at the school, but South Australia police said the boy and the school cannot be named for legal reasons.
Detective Superintendent Des Bray, head of South Australia's major crime branch, said the planned massacre would have been "catastrophic" and added it was likely it would have been carried out had it not been thwarted by police.
"We believe there was a real threat, actively planned and likely to be carried out without the actions of police," Superintendent Bray told reporters in South Australia on Wednesday.
"It is unbelievable to think this kind of thing could have happened in South Australia."
"I'm extremely grateful of the response of the local police and there is no doubt we prevented a catastrophe."
He said police became aware of the planned massacre after the teenagers began to tell others what they intended to do.
"They told some other people about what they were intended to do, and then they told other people," he said.
"I am not aware of us having an incident like this in recent times.
"Soon it became known to quite a number of people. It is believed there were no specific individuals targeted but the faculty and students."
"We believe most likely the attack would have occurred, if not stopped, before the end of the current school term."
He said an extensive investigation led to the arrest of the two teenagers earlier this month.
"Since their arrest police have conducted an extensive investigation of this matter which has included searches of several properties, the seizing of weapons, and interviews with dozens of people," he said.
"Police will allege that they intended to cause harm to a large number of people, however this plan was thwarted.
"There is no evidence to show that any other person was linked with this matter, nor did the two individuals have possession of firearms."
Detective Superintendent Bray said police first became aware of the planned attack on November 3 and both teenagers were arrested on November 10.
In letter to parents, the principal of the school in question said the duo had posed "real threat" to the school community.
The principal said they had worked alongside police on the "complex and intensive investigation" with more serious charges expected to be laid against the two teenagers.
However, the principal assured parents the school was no longer in danger.
"I wish to reinforce that [the] high school community is safe and remains safe.
"Also I can state that all action was taken as soon as possible once concerns were raised. I thank every one of you for your ongoing support of our school community and the very positive way in which we have dealt with this difficult situation."
The town's mayor said news of the alleged planned massacre had "devastated" the tight-knit community.
"It's obviously incredibly devastating for the community as well as the school community involved," he said. "We consider this to be a one-off situation and are pleased the community and police have been able to come together to stop this crime from occurring."
He urged anyone who had further information on the alleged attack to contact police.
A community forum was held in the town in relation to the incident earlier this month.
"The safety of the community has been, and remains [our] highest priority," Detective Superintendent Bray said.
"If there is any risk to the community, SA Police will take appropriate steps to advise the community in a timely manner."
The offence of solicit to murder carries a maximum penalty of life imprisonment.
Anyone with information is urged to call Crime Stoppers on 1800 333 000.