Boise (670 KBOI News) – A 13-year old boy in Boise is in serious trouble after police say he threatened a school.

The BPD got a tip Monday that the boy had made a threat against an unnamed school.  Officers questioned him and he admitted to having done it. At the time, officers could not find any evidence that he had made a bomb.

But this afternoon, officers learned that the boy had left something at an elementary school; they searched and found some kind of device. Teachers and students were told to stay inside while they checked the device out.

It was determined that it was not a threat.

The boy is under arrest in juvenile detention, on a felony charge of threatening violence upon school grounds.