The state of Massachusetts is investigating major e-cigarette manufacturer Juul on the sale and marketing minors, Attorney General Maura Healey announced Tuesday.

Why it matters: The state's probe joins the Food and Drug Administration, parents and schools in watching the "juuling" craze — an epidemic on kids who are introduced to nicotine products early. Three lawsuits have already been filed by users claiming Juul has made them more addicted to nicotine.