At that age kids just don't 'hit'... They weigh less and move slower.
It's not until kids hit puberty that things get scary. At that age you want them to know how to hit and take a hit.
I tried to find a video of kids that age playing... but here are some 9-year-olds.
https://www.youtube.com/watch?v=WxBnkZ6Gfz0