Quote from AramilTheElf
No one mentioned race until you brought it up, so that's irrelevant. And it's OK to do that here too, in certain circumstances. If someone is shooting at a policeman, he doesn't say "Oh crap, he's an American citizen, I can't shoot back!". No, he saves his own life and the lives of others and shoots. If it's not reasonable to apprehend someone, and they are a risk to the lives of others, it is perfectly legal, ethically sound, and logic to make sure they can no longer be a risk to the lives of others.
One of those things is not like the other. The Americans executed in Omega's example were not shooting at anybody when a bomb was dropped on their head. The hypothetical shooter in your example represents an immediate threat to the officer and others around him. If the suspect (and according to US law, everyone is a suspect until proven guilty) is not currently engaged in a lethal act, it is unreasonable to take leathal action against them. We don't go and shoot murder suspects just because they are assumed to have commited a murder. A citizen's rights are not suspended because they leave the country or commit a crime.