I'm a LEO and always carry CCW off-duty. As a generalized response to the OP I would most likely take no action unless life is at risk. If I am with family my primary response would be to move them from harms way, unless life is at risk. If I am alone or with other off-duty LEOs I will be a witness until the situation dictates a different response. The number of possibilities in infinite so I do not want to say "never would I". However, I would prefer to avoid pushing a situation where only property or money is at stake and no one knows me from Adam.