Nation Wisconsin teen gunned down grandparents, planned to ’cause harm’ at his high school: Police April 15, 2019Trent Tetzlaff and Chris Mueller, Appleton Post-CrescentComments Off on Wisconsin teen gunned down grandparents, planned to ’cause harm’ at his high school: Police The 17-year-old boy arrested Sunday at a Wisconsin home where two people were found dead may have planned to 'cause harm' at his high school.