Dude. Get a grip.
There is no way you'll find a "group" in the US Army that will go into town and kill women and children in their beds.
This is one guy, likely insane.
I read another account this morning that said he was seen leaving his post and walking off base and this was reported. They sent out search parties to look for him but by then he had already shot these people and was returning to base, where he surrendered.
So the villagers probably saw the search parties.