Police say the teenager, along with 18-year-old Dallin Morgan, planned to bomb an assembly at Roy High School, about 30 miles north of Salt Lake City.
Both were arrested last week. Morgan has been charged with possession of a weapon of mass destruction.
Prosecutors on Tuesday charged the 16-year-old with the same count in juvenile court, but have filed a motion seeking to try him as an adult.
The Associated Press isn't naming the suspect because he is a minor.
Police say the plot was foiled when another student came forward after receiving ominous text messages from one of the suspects hinting at their plan.
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