From the article:
A witnesses, however, told officers that Barr “had ridden up to victim and stabbed him first,” the affidavit alleges.
The article is a bit short on specifics but I can imagine, because I live near there, what happened. Just another case, Situational Awareness, The guy on the bike? What’s he looking at? One hand on the handle bars? What’s in the other hand? Is he riding away? Turning around?
Pay attention out there it can happen fast.