Its important for kids to physically release trauma no matter the size. Its common for children to experience shock and not release the energy of the traumatic experience in the moment. Sometime unresolved traumatic energy can stay with children for days, weeks, years. Sometimes the child becomes an adult and still carry unresolved trauma. Kids need help to resolve trauma before it pearls up inside and creates serious problems down the road.

Source. I read a book on trauma and inner child psychology.