Early reporting can make you nuts. Fox had a spokesperson on for police station who said there was a copy posted at the school. Don't know whether that means he was actually there or was due there. Depends on the meaning of "posted". Wish the media would be more careful.
I'm wondering if it could be high school kids, who are supposed to be in route to school, maybe report to school at a later time, for whatever reason.
It's someone who is normally on the road at that time of the morning..
There may not be a pattern. But it looks like a "thrill" killer spree.
sw