A Sky News visual investigation shows a building in Deir al Balah was hit one day after civilians were told they could flee to the city. Israel says it struck military targets in the area that day. The UN told Sky News that such strikes had "no rationale".
Just because you have some notion of what defines a child does not mean the rest of the world abides by that. Hamas will recruit kids as young as 14. Even in the US if someone under 18 commits a heinous crime, they are often tried as adults.