Welcome to Fluther.
Well yes, of course. However, if you fail to call for emergency help because “we might get into trouble”, then even if you manage to avoid legal consequences, if your friend dies or becomes permanently injured or disabled as a result of your cowardice and neglect you’d have to live with that for the rest of your life.
Which lesson would be more painful?
Another way of looking at this: Which would make the better story to tell years from now?
”... so we called the cops and the ambulance, and we got into soooo much trouble, but it was worth it because your Uncle Tim is… well, he’s your Uncle Tim; he’s as good as he can be.”
versus
”... so we ran like scared little girls and didn’t tell anyone, and we managed to avoid being caught and suspended from school. Of course, the kid died. But what the hell, he was no one I knew, so it wasn’t like a big deal or anything.”