Because that's what the evidence we have shows.
What evidence? A claim by Hamas?
Here on RF we were treated to a Hamas headline
IDF Targets Sleeping Palestinian Children!
The Hamas version was that the IDF bombed a building which they knew had sleeping children in it.
What actually happened was IDF identified a building with a large cache of missiles in the basement. Missiles intended to be fired at unknowing non-combatants. IDF let Hamas know, through an NGO go-between that the building was about to be destroyed. They had time to clear people out of the building, but not the missiles. Hamas let IDF know that children were in the building,
but left the children to die!
The missiles were destroyed and 17 children died needlessly.
But Hamas got a great headline!
Just like they do now. I think it about equally likely that some Hamas fighter deliberately shoved the medic into live fire as an IDF sniper targeted her.
Tom