Law enforcement authorities in Waseca, Minnesota, say they have thwarted a 17-year-old’s plan to kill his family, start a diversionary fire, set off bombs at an area school during lunch, kill the resource officer on campus and then shoot students.

CNN reports that John David LaDue, 17, is now behind bars due to a tip-off two days earlier, after a local woman spotted the young man acting suspiciously at a storage facility. Officers arrived to discover what looked like bomb-making materials in a locker: a pressure cooker, pyrotechnic chemicals, steel ball bearings and gunpowder. LaDue then told authorities of his plan during a police station interview. A journal recovered from his home also detailed his plan and preparations.

Originally, the teen was allegedly planning to carry out his attack on April 20, the anniversary of the Columbine High School massacre, but April 20 this year was Easter Sunday, and school was not in session.

He has been charged with four counts of attempted murder in the first degree, two counts of attempted criminal damage to property in the first degree, and six counts of possession of an explosive or incendiary device, police say.