Obviously the mother should have a talk with them but this is hardly something to call the ghestapo over.
People call the cops for anything these days...
You’re wrong, imo... This is not typical playing doctor. If it were just the 6 and 7 year old, I might agree with you (w/out the penetration part, of course) - as I agree that society is almost going around the bend as far as “zero tolerance” and the normal happenings between girls and boys at that age who are too innocent to know.
However, in this case you have an 11-year-old who is obviously old enough, to complete the act of rape, and definitely old enough to “direct” the interaction of the other child.
As horrible as it may seem, it’s a fact, and it happens more often than people want to know... Talk to a few law enforcement officers if you have any doubts. The records are usually all sealed in cases like this, but many are quite as devastating as the ones where the details all become public knowledge...