Five Tucson, Arizona, teens were arrested this week after police say they spent a week plotting the murder of a classmate at their high school. Administrators at the school alerted police after another student told them of the plan — a plan police say their investigation revealed was detailed, with one student having brought a knife to school. "The incident was not a random act of violence," police said. "The students were targeting another student in their group that they were having problems with." Two underage teen girls, two underage teen boys and an 18-year-old man were booked into jail on first-degree murder charges.