If its part of the explosions<-Enchantment<-Magic Effect then it should extend ActiveMagicEffect instead of ObjectReference.
And OnHit does not work in magic effects.
This is a script I have on one of my explosions that will 'disintigrate' the left over bodies in its area of effect. It also removes all their items to a chest, and will kill them if they are not dead yet. But it works from an explosion like you said you are doing.
Scriptname LevelersArenaDeathScript extends activemagiceffectObjectReference Property LevelersArenaChestREF AutoEvent OnEffectStart(Actor akTarget, Actor akCaster)if akTarget.IsDead() akTarget.RemoveAllItems(akTransferTo = LevelersArenaChestREF) akTarget.Delete()else If akTarget != Game.GetPlayer() akTarget.Kill() endifendifendEvent
I have plans to make a 'death' arrow, that will do about the same thing.