And two Vietnamese kids, IIRC.................
Yes, a low-hovering Huey helicopter destabilized by explosions crashed and killed Vic Morrow and two children...who, as I understand it, were too young to act, and whose parents had not been told of the scene they would be appearing in.
Some famous actor refused to work with that director ever again, because the director was largely responsible for the circumstances that led up to the accident, and he claimed the director laughed it off afterwards.