In Bartosh v. Banning (1967) 251 Cal.App.2d 378, the plaintiff was an innocent bystander injured during a bar fight which occurred while the bartender was out of the room on a telephone call. The Bartosh court said: "One who operates a bar where the public is invited must use reasonable care to protect his invitees against injury through the negligent or wrongful acts of other invitees on the premises where he has reasonable cause to anticipate such acts and the probability of injury resulting therefrom." (Bartosh, at pp. 383-384.) Although not expressly overruled, the Bartosh court employed an earlier formulation of the test for duty that would require a bar operator "to take action only when he has reason to believe, from what he has observed or from past experience that the conduct of the other will be dangerous to the visitor." (Id. at p. 384.) The court held that it was a question for the trier of fact whether a person in charge of the premises, in the exercise of ordinary care, should have observed the conduct of the offender, realized it was likely to result in injury and stopped it. (Ibid.) The appellate court addressed the trial court's decision not to provide the jury with additional guidance: "Where the trial court has given instructions which are inadequate, or are so scanty as to leave the jury without a full understanding of the law applicable to the case, and this lack of understanding is brought to the attention of the court by the jury's request for further guidance," it is "'incumbent on the trial court to give instructions on all the vital issues in the case so that the jury would have a full and complete understanding of the law applicable to the facts.'' The responsibility for adequate instruction becomes particularly acute when the jury asks specific guidance.'" (Id. at p. 387.)