For that matter I don't understand why they were running on your car! perhaps their skateboard developed a brain and decided to take a detour under your car, causing the child to take a leap of faith over and tripped on the top, got the ariel stuck in their leg and as they fell off, fracturing their elbow as they hit their skate board which expeditiously vacated the vacinity, mangling your aerial in the wheels and dragging the fellen down the street leaving fragments of cheekbone peppered along your drive! :-D
or as Neil rightly put it, they are just Gits