Updated

Authorities on Tuesday charged a 16-year-old boy with a felony in what they say was a plot to detonate a bomb at a Utah high school.

The teenager, along with Dallin Morgan, 18, had planned for months to bomb an assembly at Roy High School, about 30 miles north of Salt Lake City, then steal a plane from a nearby airport and flee the country, police said.

Both were arrested last week. Morgan has been charged with possession of a weapon of mass destruction. He is set for a court appearance on Wednesday and faces a possible life sentence if convicted on the first-degree felony charge.

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 defendant's emotional attitude, pattern of living, environment and home life demonstrate that he has sufficient maturity to appreciate the seriousness of these charges and to be tried as an adult," prosecutors wrote in the motion filed Tuesday in Ogden's 2nd District Court.

The Associated Press normally does not identify juveniles who are suspects in crimes or charged in juvenile court.

Telephone messages left at the homes of both suspects were not returned Tuesday.

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.

"If I tell you one day not to go to school, make damn sure you and your brother are not there," one message read, according to court records. "We ain't gonna crash it, we're just gonna kill and fly our way to a country that won't send us back to the U.S.," read another message.

Police said the two teens had a detailed plot, blueprints of the school and security systems, but investigators have so far found no explosives in multiple searches. Authorities have also said the suspects spent hundreds of hours training on a home computer flight simulator and studying manuals to prepare to steal a plane after the bombing.

While police don't have a motive, one text message to the fellow student noted they sought "revenge on the world."