Negligence isn't strict liability (ie you are not automatically at fault because someone dies through your actions - accidents are recognised to happen). It also doesn't require intent, only recklessness. But the test of recklessness does take into account the age of the defendant and their ability to assess what the consequences of their actions might be (ie the younger the child, the less likely they are to be found negligent).
Again, being sued in negligence is nothing to do with being prosecuted in the criminal courts. The child won't have a criminal record and, more likely than not, will have very little to do with the actual proceedings.
The only way to avoid this situation is to nationalise personal injury and death compensation, so that the State pays (which is what happens in NZ). There are advantages and disadvantages to both systems.