It's an obvious point made a million times, but if you're a guy with a gun and see another guy with a gun don't you think he might be a bad guy? If you're a guy without a gun and you see a bunch of yahoos with guns, don't you think they're probably bad guys? If you're cops with guns and you are called to respond to a situation, aren't you going to assume the guys with guns are the bad guys? Because guns.
