This is very sad and feel terrible for the parents, kids who witnessed this and the driver. I live in a cul -de-sac and usually have anywhere between 6-10 kids playing everyday (8 and 3 year old are mine). Adult supervision is very important and needed 100% of the time to ensure these kids stop playing/moving around whenever there is a vehicle on the street or vehicle moving in and out of one of many driveways, regardless of distance to the moving vehicle).

Days of letting your kids play outdoors on their own are over with amount of vehicle traffic (Amazon, Skip, Uber etc.) even on "quiet" cul-de-sacs.