WASECA, Minn.

- Prosecutors are seeking adult charges for a southern Minnesota teen who authorities say had planned to kill his family and bomb the junior and senior high school in Waseca.

KTOE-AM reported that Waseca County prosecutors filed a motion yesterday asking that the teen be charged as an adult. A hearing is set for May 12.

Police arrested the 17-year-old this week and charged him in juvenile court with multiple counts of attempted first-degree murder, possessing explosive or incendiary devices and criminal damage to property.

A juvenile petition said he told police he intended to kill "as many students as he could."

Police Capt. Kris Markeson said authorities believe the teenager was acting alone and would have carried out the attack in the next few weeks if he hadn't been caught.

Markeson said he was disturbed by the amount of guns and other material the youth obtained. He said he could not divulge if specific students were targeted. He said police were tipped by a resident who reported a suspicious person at a self-storage facility.

"This case is a classic example of citizens doing the right thing in calling the police when things seem out of place. By doing the right thing, [an] unimaginable tragedy has been prevented," Markeson said.

School Superintendent Thomas Lee said the 11th-grader was known to school officials but they had no major issues with him. He said teachers tried to reach out to him, but he was shy.

"We have escaped what could have been a horrific experience," Lee said.

The investigation began in late March after three small explosive devices were discovered at an elementary school playground in the city of 9,400 people, about 80 miles south of Minneapolis. The youth allegedly admitted setting off practice bombs there.

According to the charging documents, the Free Press of Mankato reported, the suspect kept a 180-page notebook that detailed his plans. He allegedly told police he planned to shoot his mother, father and sister, then start a fire in a rural field to distract first responders while he went to the school to set off pressure-cooker bombs in the cafeteria. He also allegedly planned to throw Molotov cocktails, gun down students and kill a school liaison officer while he helped injured students.

He said his ultimate goal was for a SWAT team to kill him.

The teen allegedly referenced the Columbine, Virginia Tech and Sandy Hook school shootings in his notebook, and idolized the Columbine shooters.