 From indications from watching the counter-sniper video, it looks like the counter-sniper saw the threat and took action against the threat. There's been reporting that local law enforcement may have seen the shooter ahead of time, may have interacted with the shooter ahead of time. I'd be interested to find out if that is factual and how that all played out. I'll also point out that if you watch the video with the counter-sniper, the counter-sniper fires. It looks like they fire their weapon first.