The teen, whose exact age Holt did not know, had posted a photo of himself holding a gun, eliciting the school-shooting comment.
Officers went to the teen’s West Jordan home, Holt said, and arrested him. The boy is not a student at Joel P. Jensen Middle School, Holt said, but he “has ties to it.”
Several similar threats have followed the shooting at a school in Parkland, Fla., that killed 17 people in February.