Why does everybody get offended when people ask about black people being dangerous?

I mean like I've seen some questions that ask why are black people dangerous and the first answers are always "YOU'RE RACIST BLAH BLAH BLAH" then they try to prove a point by saying most of the infamous serial killers are white, but they completely miss the point of the question. I'm sure there are dangerous people that are White Asian and Hispanic but the person was asking about black people and so many people get offended and try to pin the blame on other races or call it racism. I'm just wondering why so many people are getting offended then try pinning the question on other races.