The two teens had a detailed plot, blueprints of the school and security systems, but no explosives. They had hours of flight simulator training on a home computer and a plan to flee the country, but no plane.
Still, the police chief in this small Utah town said, the plot was real.
"It wasn't like they were hanging out playing video games," Roy Police Chief Gregory Whinham said Friday. "They put a lot of effort into it."
Dallin Morgan, 18, and a 16-year-old friend were arrested Wednesday at Roy High School, about 30 miles north of Salt Lake City, after a fellow student reported that she received ominous text messages from one of the suspects.
"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.
While police don't have a motive, one text message noted they sought "revenge on the world."
The suspects say they were inspired by the deadly 1999 Columbine High School shootings in Littleton, Colo., and the younger suspect even visited the school last month to interview the principal about the shootings and security measures.
However, one suspect told authorities it was offensive to be compared to the Columbine shooters because "those killers only completed 1 percent of their plan," according to a probable cause statement.
The teens had so studied their own school's security system that they knew how to avoid being seen on the facility's surveillance cameras, authorities said.
Whinham said the "very smart kids" had spent at least hundreds of dollars on flight simulator programs, books and manuals, studying them in anticipation of carrying out their plan to bomb an assembly at the 1,500-student high school.
While authorities said the suspects believed they could pull it off, experts said, it would have been a long shot.
Royal Eccles, manager at the Ogden-Hinckley Airport, about a mile from the school, said it would have been nearly impossible for the students to steal a plane or learn to fly one using flight simulator programs.
Whinham said it appeared the suspects, who have no criminal history, also had prepared alternate attack plans, but he declined to elaborate. He also declined to say whether any firearms were found during their searches.
While authorities have said they have not found any explosives, they charged Morgan on Friday with possession of a weapon of mass destruction.
Morgan has been released on bond, pending a court hearing Wednesday. The 16-year-old, whom the Associated Press isn't naming because he's a minor, remained held pending further court hearings.
In Colorado, Columbine Principal Frank DeAngelis confirmed Friday he met with the 16-year-old suspect Dec. 12 after the teenager told him he was doing a story for his school newspaper on the shootings.