MINNEAPOLIS — The 17-year-old Minnesota boy outlined his plan in a 180-page journal: kill his family, set a fire to divert first responders, then go to his school with bombs and guns and “kill as many students as he could,” according to court documents.

The planned attack in Waseca, a city of about 9,400 people about 80 miles south of Minneapolis, was halted this week when a concerned citizen became suspicious and called police. When authorities responded, they say they found guns, bombs and other materials — all allegedly amassed by a teenager working alone as he methodically plotted his steps and conducted experiments to refine his plan to inflict bloodshed before being killed by responding officers.

“The bomb squad members were shocked by the amount of bomb making chemicals and components (the teen) had,” court documents say. “Bomb squad members said they have never seen that much of some of those chemicals in one place.”

The teen was arrested this week and charged in juvenile court with multiple counts of attempted first-degree murder, possessing explosive or incendiary devices and criminal damage to property. Prosecutors in Waseca County filed a motion Friday asking that he be charged as an adult, according to documents first obtained by KTOE-AM.

Police were not commenting Friday, and messages left with the teen’s family were not returned. Friday was a planned staff training day at the junior high and high school building that was the target of the alleged plot, and students did not have classes.

“I think there’s a range of emotions right now. We’re all disturbed,” said school Superintendent Thomas Lee. While he said he’s confident the threat is gone, emotions range from: “‘Should we have seen this coming? Did we miss something?’ to ‘Wow, I really like this kid,’ … to ‘Wow, this could have actually happened in our school and our town.'”

Police have not released a motive, though court documents made public Thursday paint an image of a boy who idolized at least one of the gunmen in the Columbine school shooting.

Lee said the reserved teenager was well-liked and had friends.

According to court documents, the teen first planned to fatally shoot his mother, father and sister, then start a fire in a rural location to draw first responders away from the city.

He then planned to go to the school and detonate two pressure cooker bombs filled with shrapnel near the cafeteria. Then, while the school liaison officer was helping injured students, he planned to shoot and kill him, documents say.

From there, he wanted to “kill as many students as he could” by setting off pipe bombs and throwing Molotov cocktails, then shooting students as they rushed into the hall, the documents say.

Authorities say the teen’s 180-page journal outlines the elaborate plan, complete with his research on chemicals, which he knew by scientific name, shrapnel and blast radiuses.

His first entry was made July 24. The overall plan hadn’t changed much since, but the teen tweaked the materials, detonators and other items he planned to use and conducted experiments to find what would “provide the most flash, fire capability, and would cause the most deaths,” documents say.

In the journal, he also outlined steps that would get him to his goal, including getting a job so he could buy supplies, opening a PayPal account so he could buy items online, renting a storage unit and stealing weapons.

Authorities believe he would have carried out his attack in the next couple of weeks if he hadn’t been stopped.

A tip led police to the boy’s storage unit, which police say was rented by a friend’s mother. There, they arrested the teen Tuesday, after finding him with bomb-making materials.

In the boy’s bedroom, investigators found seven firearms, ammunition and three bombs. Between the boy’s home and storage unit, they also recovered a massive amount of chemicals and bomb-making materials, including fuses and wires, bottles of smokeless powders, a ski mask, a trench coat and 60 pounds of ball bearings.

The teen’s next court date is May 12. He’s being held at a juvenile prison in Red Wing.