Typical of the liberal mentality, they can't win in a debate of words so they take up weapons against the unarmed. What pussies!
Which is precisely why they want us all to be unarmed.
You'll note that is happened among 17-year-olds, within the perimeter of a public-school/guaranteed defenseless victim zone.
Perhaps the reason it hasn't happened among adults is that Minnesota passed concealed carry in 2003 and Republican adults were lining up to take the carry classes.