In Germany, where there is stricter gun control, there was an incident in which a bystander tackled the knife attacker. The police mistook the bystander as the perpetrator, and because the police were distracted, the attacker got up and stabbed two more people including one of the police officers. https://apnews.com/article/germany-mannheim-stabbing-police-officer-death-a66c14970a53464aff0c1c77a7196481

I agree with others. The idea of “good guy with a gun will stop the bad guy with a gun” is pretty much wishful thinking if the police arrives on the scene and mistakes who. It does not matter whether there is gun control or not, the good guy could be mistaken in the midst of chaos.