870.05 When killing excused.—If, by reason of the efforts made by any of said officers or by their direction to disperse such assembly, or to seize and secure the persons composing the same, who have refused to disperse, any such person or other person present is killed or wounded, the said officers and all persons acting by their order or under their direction, shall be held guiltless and fully justified in law; and if any of said officers or any person acting under or by their direction is killed or wounded, all persons so assembled and all other persons present who when commanded refused to aid and assist said officer shall be held answerable therefor.