Roy, Utah student Bailey Gerhardt, 16, alerted Roy High School about a suspicious text message, which foiled plans by two classmates who were allegedly plotting to set off a bomb during a school assembly and escape in a stolen airplane.
Gerhardt told The Salt Lake Tribune that she received the text from a 16-year-old boy that asked: "If I told you to stay home on a certain day, would you?"
The boy, whose named hasn't been released because he's a minor, and 18-year-old Dallin Morgan (pictured) were pulled out of school Wednesday and arrested.
Roy police spokeswoman Anna Bond said Thursday: "It was the work of a very courageous student who came forward. It could have been a disaster."
Gerhardt said the 16-year-old was angry because he was recently dumped by his girlfriend. She said he had told her he had looked into the 1999 mass shootings at Colorado's Columbine High School.
Chief of Police Gregory Whinham said the Roy High School plot was months in planning and included plans for a device designed to cause as much harm as possible to students and faculty at the school.
Police also discovered the two teens had trained on flight simulation software for their getaway.