Police officer in Wisconsin shot the active shooter at the sikh temple from 75 yards away, according to this LA Times report. It was only then that the shooter took his own life. The officer has been described as a "tactical expert" among his peers. He is also a firearms instructor.
It was alluded in the aforementioned article that the officer shot the suspect with a patrol rifle. Patrol rifles are in the AR-15 family, meaning they are .223s. It is important to note that if you zero your rifle at 25 yards, point of aim/point of impact, then at 75 yards the shot will go high and you may miss your targets. Hold low at 75 yards if that is the case.
Zeroing at 100 yards is much better. You don’t want to have to play
For those officers or honorable citizens who may not happen to have an AR handy when bad things happen (think Murphy’s Law here), check out the video I made for Guns.com above. I took a 100 yard shot at a police pistol range with a couple of cop friends of mine.
Train for the worse and expect the best. Stay safe. Train hard. Train smart. And fight to win.
To read amazing interviews with warriors, check out Warrior SOS: Interviews, Insights and Inspiration, the book on Amazon.com. Here's the link: http://www.amazon.com/dp/B00D3WO7VK