I thought the same thing, but about how there was no debris on the rifle but a ton of the body.
Yes I have seen no proof that is the weapon used by the perp. That pic could be from anywhere. It does not appear to have sustained any type of damage that you would expect in a bomb explosion. Like I said the sight is pristine. I have a Bulgarian AK 74 and this looks more like an AK 47 to me. Early reports said the weapon was an SKS. So who knows? or as somebody else mentioned maybe more than one shooter.