WASECA, Minn. - Prosecutors say police in Waseca likely foiled a planned school massacre when they arrested a teenager in connection with the March discovery of explosive devices on the grounds of a local elementary school.

A juvenile petition says John David LaDue, 17, of Waseca, is charged with four counts of attempted first-degree murder, six counts of possessing explosive devices and and two counts of first-degree criminal damage to property. All the charges reportedly involve a plot to kill his parents, his sister, and then a school liaison officer and as many students as he could.

At a 3:00 p.m. news conference on Thursday, Capt. Kris Markeson of the Waseca Police Department told reporters that authorities believe LaDue was acting alone. He says he believes LaDue would have succeeded if he had not been caught.

A visibly shaken Markeson said he was disturbed by the amount of guns and other material LaDue obtained.

"He intended to set off numerous bombs during the lunch hour and kill the school resource officers and set fires and shoot students and staff," Markeson said.

Waseca's story is a story we wished could have been told the day before Sandy Hook and the night before Columbine.

"The information that has been revealed is that we've escaped what could have been a horrific experience," said Waseca Schools Superintendent Tom Lee.

The investigation began March 24, when melting snow revealed a pair of devices on the Hartley Elementary School playground in Waseca. Police say one of the devices had detonated while the second had failed to ignite.

Four days later a third device was found inside of a stuffed toy. It was already detonated.

On Tuesday, just over a month after the discovery of the explosives, 911 was called by a person who saw LaDue going into a storage unit and the caller thought he looked suspicious going in and out with a backpack.

Waseca Police arrested LaDue after executing search warrants at a residence and at the storage facility in Waseca.

A juvenile complaint says LaDue was arrested in a locker at the storage facility, surrounded by materials to make explosives. When pressed by officers LaDue allegedly told authorities he would talk to them at the police station.

Once there, detectives say LaDue detailed an elaborate plot that started with murdering his mother, father and sister with a .22 caliber firearm. LaDue then planned to go to a remote area outside Waseca to start fires that would pull first responders out of town. At that time, investigators say, LaDue planned to go to the middle and high school campus during lunch and set off pressure cooker bombs to kill students. When the school police liaison officer responded, LaDue planned to shoot him, and then open fire on more students.

"During his interview with officers, LaDue revealed his plan was to kill his family members, start a diversionary fire in rural Waseca to distract first responders and then travel to Waseca Junior and Senior High School," said Capt. Markeson.

LaDue allegedly told authorities that he was fascinated by the school shootings at Sandy Hook, Virginia Tech and Columbine, and idolized Columbine shooters Eric Harris and Dylan Klebold.

Police say LaDue told them the plot was written down in a notebook and kept in a locked guitar case in his room. LaDue also said he had an assault rifle, a number of handguns and 400 rounds of ammunition in a gun safe that was also in his room. Search warrants were issued, and police recovered seven firearms, ammunition, and three functional bombs from LaDue's home, along with black clothing and a ski mask.

The Bloomington bomb squad searched the storage unit and found three additional completed explosive devices and materials to make many more. Members of the bomb squad told prosecutors they were shocked by the volume of bomb-making materials and components LaDue had.

Based on statements from LaDue and items found in his home and storage locker, authorities believe the massacre was to take place in the next week or two.

Police said LaDue planned to die in the attack.

It's a story hard to hear by those who knew LaDue personally, like his guitar teacher of four years, Ryan Lano.

"I taught him guitar, met him when he was 13 years old," Lano said from his studio in St. Peter where he taught LaDue his last lesson in December of 2013.

Lano said LaDue was a model student who was a very talented musician, so Thursday's news was as unwelcome as it was unsettling.

"Only adjective I can come up with is I'm shocked at the information, this is new to me," Lano said.

"It's not like he was unknown to us. He was known. People made lots of contact with him. We tried to do everything we possibly could do to build relationships with him as well. But sometimes even when you're trying to do everything possible it doesn't turn out the way you want it to," Superintendent Lee added.

Ladue is in juvenile custody in Red Wing.

He was transferred there from Rochester after he made, what authorities are calling, "homicidal statements."

KARE 11 tried repeatedly to speak to LaDue's family in Waseca but never got a response.

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