As someone who was once a kindergartner, I'm going to go out on a limb: yes, they probably did. They're six years old, for chrissakes. What the hell do they know? But, oh god- this is headline news! The police are investigating.
Hi, I'd like to welcome you to reality. Over here, children are curious and don't know all of our social mores. Since their nerves function largely the way ours do, they at least understand that touching certain parts of their bodies feels good. They're probably vaguely aware of the taboo, But they don't understand it. Why not? Because they're children! Are there no child psychologists anywhere in that school district? Nobody to explain that this is pretty normal behavior for very young children?
Public schools, we give your children psychological issues that will plague them for decades so you don't have to.