I concur in the judgment holding that defendant was properly convicted of the first degree murder of Reynaldo Estrada. I write separately to clarify why his conviction is proper even though neither defendant nor his codefendant Gonzalez intended to kill Estrada and even though it could not be determined with the necessary degree of certainty whether defendant or Gonzalez fired the fatal shot. I write separately also to explain how this case differs from the companion case of People v. Cervantes (2001) 26 Cal.4th 860 [111 Cal.Rptr.2d 148, 29 P.3d 225], in which I concur in this court’s opinion and judgment holding that Cervantes’s first degree murder conviction was improper.
The majority gives a detailed summary of the relevant facts, which need not be repeated here, and it explains that the evidence at trial was insufficient to establish whether defendant or Gonzalez fired the bullet that killed Estrada, although it is certain that one or the other did. In this situation, a reviewing court must examine both possibilities—that defendant fired the fatal shot, and that codefendant Gonzalez did so—to determine whether the evidence supports defendant’s conviction.
To support a criminal conviction, there must be sufficient evidence of both the criminal act and the required mental state. (Pen. Code, § 20 [“In *855every crime or public offense there must exist a union, or joint operation of act and intent, or criminal negligence”].) I consider first the criminal act requirement.
For first degree murder, the criminal act is “the unlawful killing of a human being.” (Pen. -Code, § 187, subd. (a).) If defendant fired the shot that struck and killed Estrada, then the criminal act requirement presents no difficulty: Defendant performed the prohibited act by killing Estrada, a human being. If Gonzalez rather than defendant fired the fatal bullet, the legal analysis is more complicated, although defendant’s guilt is also established by sufficient evidence.
In legal terms, defendant committed the act of killing Estrada if his conduct was a legal or proximate cause of Estrada’s death, even though codefendant Gonzalez fired the bullet that struck and killed Estrada. (See LaFave & Scott, Criminal Law (2d ed. 1986) § 3.12, p. 277 et seq.) Defendant and Gonzalez were members of rival gangs. By challenging Gonzalez with gestures and hand signals, and by firing his gun at Gonzalez, defendant engaged Gonzalez in a gun battle and induced Gonzalez to fire the shot that hit an innocent bystander, Estrada. In this sense, it is accurate to say that even if defendant did not fire the bullet that killed Estrada, nonetheless defendant’s conduct caused Estrada’s death.
The Court of Appeal recognized that if Gonzalez’s bullet killed Estrada, it was defendant’s conduct that prompted Gonzalez to shoot, and in that sense had also caused Estrada’s death, but the court expressed the view that defendant’s conduct could not be a proximate or legal cause of Gonzalez’s actions. It reasoned that in convicting Gonzalez of first degree murder, the jury must have concluded that Gonzalez fired at defendant with a deliberate and premeditated intent to kill defendant. The Court of Appeal thought that this deliberate conduct by Gonzalez must in law be regarded as a “superseding cause” that cut off defendant’s responsibility for any injury or death inflicted by the bullets that Gonzalez fired.
In law, the term “superseding cause” means “an independent event [that] intervenes in the chain of causation, producing harm of a kind and degree so far beyond the risk the original [wrongdoer] should have foreseen that the law deems it unfair to hold him responsible.” (Soule v. General Motors Corp. (1994) 8 Cal.4th 548, 573, fn. 9 [34 Cal.Rptr.2d 607, 882 P.2d 298].) Here, defendant and Gonzalez during their gun battle were attempting to kill each other, so that the killing of a bystander was a harm that both in kind and degree was within the risk that defendant and Gonzalez must have expected. Because they each expected and intended a death to occur, and a death did *856occur in a manner that was entirely foreseeable, it does not matter, for purposes of determining proximate or legal cause under criminal law, that the person killed was not the precise object of their lethal intent.
Significantly, we are not faced with a situation in which the mental state of the person who fired the fatal shot was substantially more culpable than the mental state of the person who induced the shooter to act. Here, both defendant and Gonzalez acted with intent to kill, and the evidence was equally persuasive that for both of them the intent to kill was deliberate and premeditated. Because defendant and Gonzalez had equally culpable mental states and engaged in precisely the same conduct at the same time and place in exchanging shots, it is not unfair to hold them equally responsible for Estrada’s death, without regard to which of them actually fired the bullet that struck and killed Estrada.
I consider next whether defendant had the required mental state for first degree murder. Under the statutory definition of that crime, the required mental state may take different forms. Here, the prosecution argued that defendant had the required mental state under either, or both, of two theories. The prosecution argued that in killing Estrada, defendant acted with a mental state sufficient for first degree murder because he had formed a deliberate and premeditated intent to kill Gonzalez, and because defendant killed by “discharging a firearm from a motor vehicle” at a person outside the vehicle with the intent to kill the person at whom the shot was fired. (Pen. Code, § 189.)
If defendant committed the prohibited act, either by firing or by inducing Gonzalez to fire the fatal shot, with a deliberate and premeditated intent to kill Gonzalez, then he had a mental state sufficiently culpable for first degree murder. Under the rule of transferred intent, as the majority explains, a defendant who intends to shoot and kill another but, because of bad aim, kills a different person is “just as guilty as if he had actually harmed the intended victim.” (LaFave & Scott, Criminal Law, supra, § 3.12, p. 284; see also People v. Scott (1996) 14 Cal.4th 544, 549 [59 Cal.Rptr.2d 178, 927 P.2d 288].) For purposes of applying the rule of transferred intent, it does not matter whether defendant himself fired the fatal shot or instead induced or provoked another to do so; in either situation, defendant’s culpable mental state is determined as if the person harmed were the person defendant meant to harm. (See People v. Antick (1975) 15 Cal.3d 79, 88-89 [123 Cal.Rptr. 475, 539 P.2d 43].)
Under the prosecution’s other mental state theory—a killing while firing from a motor vehicle—it is unnecessary to apply the transferred intent rule. *857Under the Penal Code, a murder is of the first degree if it was “perpetrated by means of discharging a firearm from a motor vehicle, intentionally at another person outside of the vehicle with the intent to inflict death.” (Pen. Code, § 189.) Nothing in this statutory language requires that the person killed be the person whom the defendant intended to kill; rather, it is enough that the defendant acted with the intent to kill the person at whom he or she was shooting. Here, because defendant shot from a car at Gonzalez, who was outside the car, with the intent to kill Gonzalez, and because this conduct was the proximate or legal cause of innocent bystander Estrada’s death, defendant had a mental state sufficiently culpable for a first degree murder conviction.
On the surface, this case resembles the companion case of People v. Cervantes, supra, 26 Cal.4th 860. In both, the defendant was a gang member who discharged a firearm at someone belonging to a rival gang. In both, the defendant’s conduct induced additional gunfire in which a third person died. But this court has concluded that these similarities are less significant than other circumstances distinguishing the two situations, so that the defendant in Cervantes may not be convicted of the third person’s murder. Here, defendant and Gonzalez were firing at each other when a bullet from one of their guns hit bystander Estrada. In Cervantes, the defendant fired at Linares, after which Linares’s fellow gang members shot and killed Cabrera. Because the person at whom the defendant had fired (Linares) did not participate in the killing of Cabrera, and because Cabrera was not killed during an exchange of shots at a single time and place, proximate or legal causation is not established.
History sadly establishes that killings motivated by revenge may occur in cycles lasting many years and even generations. Although those whose conduct precipitates these vendetta cycles, and all who participate in continuing them, must bear moral responsibility for the ensuing bloodshed, the criminal law will not impose what in theory could be an unbounded liability for retaliatory killings, and courts must try to draw appropriate lines to mark the outer limits of legal causation in these situations. The court’s decisions today in these two companion cases should begin to fix this line of demarcation separating mutual combat killings from retaliatory killings in the context of urban warfare between rival street gangs.
Werdegar, J., concurred.