A 13-year-old Arizona middle school student has been arrested on terrorism charges for threatening to “shoot up the school” last week on his bus ride home.

The Yavapai County Sheriff’s Office said it investigated after the bus driver contacted Prescott Mile High Middle School officials, telling them the student “made the threat three times” before he got off the bus near his home.

School officials contacted the boy’s mother and police.

When deputies met with the teen and his mother, the boy “admitted to repeatedly telling the bus driver that he was going to shoot up the school.”

“He said the reason he did so was to distract the bus driver while his friend moved to the back of the bus, but that he had no real intention of doing any harm at the school,” deputies said.

The boy was charged with threatening or intimidating, interference or disruption of an educational institution, and making a terrorist threat, the sheriff’s office said.

“I want to speak to directly to the young people out there,” Sheriff David Rhodes said. “I cannot stress enough the seriousness of making a threat to a school, even if you are ‘just kidding.’ You will be arrested and charged for making these types of dangerous threats. ‘I wasn’t serious’ isn’t a defense, so please be aware that your words have consequences.”

The sheriff’s office said it advised the boy’s mother to change the combination of the family’s gun safe after she told them there were firearms in the home, locked into the safe.

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[Featured image: Prescott Mile High Middle School/Google Maps]