 Now, if you're a golfer, I'm not, but I know golfers use rangefinders too. But this guy wasn't up there with an iron. He was up there with an AR-15. So he manages to get all the way to the roof of the building. He's spotted almost half an hour before the first shots ring out. The police are alerted and do nothing meaningful. The Secret Service is alerted and do nothing meaningful. And even the snipers on the adjacent roof about 100 yards away, they apparently spot the man.