my sons daycare put the 3 year olds in his class and one of the 3yo hit my son and 3 other kids and…

my sons daycare put the 3 year olds in his class and one of the 3yo hit my son and 3 other kids and left marks on the 3 other kids like why do y’all even have 3 year olds in a room with 1 year olds?! Doesn’t make sense to me at all. And if he’s going around hitting kids clearly they were not supervising the kids like they should but when I called to report it to the director she says “it happens” 🙄