The teenager had a plan.
According to authorities in Waseca, Minnesota, he was going to kill his family, start a diversionary fire, set off bombs at an area school, kill the resource officer there and then shoot students.
Frighteningly, the 17-year-old - who CNN is not naming because of his age - had the resources to carry out such an attack.
But because of watchful eyes, he didn't have the chance and is now behind bars.
"This case is a classic example of citizens doing the right thing and calling the police when things seem out of place. By doing the right thing, unimaginable tragedy has been prevented," the Waseca Police Department said in a Thursday statement.
Police were tipped off to the case two days earlier. Someone called about a suspicious person at a storage facility. When officers arrived, they saw what looked like bomb-making materials in a locker - a pressure cooker, pyrotechnic chemicals, steel ball bearings and gunpowder.
The teen went with officers to the police station for an interview.
There, police say, he told authorities of his plan to kill his mother, father and sister, start a fire in rural Waseca to distract first responders, go to the Waseca Junior and Senior High School, where he planned to set off various bombs during lunch, kill the school resource officer, set fires, and then open fire on students.
A journal recovered from his home detailed his plan and preparations, said police, who believe he meant to carry out the attack in the next week or two.
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If she had been at the scene of the crime, forensic evidence would prove her guilt, but Amanda Knox says there is nothing - no DNA, no hair, no footprints, no handprints - to show she was there.
Knox spoke in an exclusive interview with CNN on Thursday, two days after an Italian court released an explanation of her conviction.
In a retrial, Knox and Raffaele Sollecito, her then-boyfriend, were found guilty in the 2007 death of Meredith Kercher, Knox's onetime roommate.
"I did not kill my friend. I did not wield a knife. I had no reason to," Knox said.
"In the month that we that we were living together, we were becoming friends. A week before the murder occurred, we went out to a classical music concert together ... We had never fought."
Knox struggled to speak at moments in the interview, seemingly overcome by emotion and thoughts of Kercher. But, for the most part, she was calm, collected and methodical in how she broke down arguments in the case.
In its more than 300-page document, the Florence appeals court said a third person convicted in the murder, Rudy Guede, did not act alone, and cited the nature of the victim's wounds.
Ruling Judge Alessandro Nencini, who presided over the second appeal in the case, said Kercher and Knox disagreed over the payment of the rent in the house they shared in Perugia and that "there was an argument then an elevation and progression of aggression."
Knox dismissed those allegations out of hand.
"If I were there, I would have traces of Meredith"s broken body on me. And I would have left traces of myself around - around Meredith's corpse," she said.
"And I - I am not there. And that proves my innocence."
MORE ON THE SAGA:
Italian court explain Amanda Knox conviction
By Barbie Latza Nadeau, CNN, Wed April 30, 2014
An Italian court says it convicted Amanda Knox and her former boyfriend of murdering her onetime roommate in part because of evidence showing that more than one person killed the British student.
The Florence appeals court released its explanation Tuesday, less than three months after it convicted Knox and Raffaele Sollecito in Meredith Kercher's 2007 death in a retrial.
In the more than 300-page document, the court said that a third person convicted in the murder, Rudy Guede, did not act alone, and cited the nature of the victim's wounds.
ONE YEAR AGO:
Last year, May 2013, Chris Cuomo sat down with Knox and she told him she's scared to return to Italy to face a new trial nearly six years after her study-abroad roommate's slaying. But she's considering it.
"I'm afraid to go back there," she said.
"In Italy," she added, "people think it's arrogant of me to sit here in the United States and have a book come out and defend myself. And first of all, I find that incredibly unfair, because I have the right to defend myself. And no one can ask me to just shut up because it's convenient. But at the same time, I want to prove to them that I care about what's going on."
Four men and one woman died - two who suffered heart attacks and three who were crushed, said Interior Minister Rodrigo Penailillo.
About 300 prisoners escaped from the northern port city of Iquique in the immediate aftermath, he said.
The quake struck about 8:46 p.m. local time, some 60 miles northwest of Iquique. It had a depth of 12.5 miles, the U.S. Geological Survey said.
Chile's National Emergency Office asked coastal residents to evacuate.
"The fact is, we will know the extent of the damage as time goes by and when we inspect the areas in the light of day," Chile's President Michelle Bachelet said early Wednesday. "The country has faced these first emergency hours very well."
Residents in the port city of Antofagasta walked calmly through the streets to higher ground as traffic piled up in places.
"Many people are fearful after experiencing the powerful earthquake in 2010, so they immediately fled for higher ground when they heard the tsunami warning," said Fabrizio Guzman, World Vision emergency communications manager in Chile.
"There have been multiple aftershocks and communications have been cut off in many of the affected areas. So people are waiting in the dark hills not knowing what is to come, and hoping they will be able to return to their homes safely."
The Pacific Tsunami Warning Center issued several tsunami warnings, but canceled all of them by early Wednesday. Tsunami watches, which initially extended as far north as Mexico's Pacific coast, were called off as well.
Tsunami waves of more than 6 feet generated by the earthquake washed ashore on the coast of Pisagua, according to Victor Sardino, with the center.
Iquique, with a population of more than 200,000, saw 7-foot waves.
An earthquake of the scale that struck Tuesday night is capable of wreaking tremendous havoc.
So, if the initial reports stand, Chile may have dodged a major catastrophe.
Landslides damaged roads in some regions. Power and phone outages were reported in others.
Chile is on the so-called "Ring of Fire," an arc of volcanoes and fault lines circling the Pacific Basic that is prone to frequent earthquakes and volcanic eruptions.
On March 16, a 6.7-magnitude earthquake struck 37 miles west-northwest of Iquique. A 6.1-magnitude hit the same area a week later.
About 500 people were killed when an 8.8-magnitude earthquake struck Chile on February 27, 2010. That quake triggered a tsunami that toppled buildings, particularly in the Maule region along the coast.
According to researchers, the earthquake was violent enough to move the Chilean city of Concepcion at least 10 feet westward and Santiago about 11 inches to the west-southwest.
'No hazards' to U.S. coastline
The U.S. National Tsunami Warning Center worked Tuesday to determine the level of danger for Alaska, Washington, Oregon and California, as well as Canada's British Columbia.
Gerard Fryer, a geophysicist with the Pacific Tsunami Warning Center, told CNN there is "clearly not going to be any hazards to the coastline of North America."
The Pacific Tsunami Warning Center issued a tsunami warning for Hawaii, saying strong currents may pose a hazard to swimmers and boaters.