Originally Posted by Rochard

I had the news on just now while eating breakfast - I haven't really watched the news in the past week or so - and it seems this now is the case.

And?

It means as the investigation continues and they are putting together a timeline. All we knew before was that the shooter engaged the security guard. The security guard was alerted to his room (or a nearby room) by an open door alarm. The gunman most likely saw the security guard on his cameras, assumed the worst, and opened fire.

See not seeing anything out of the ordinary here.