Can I get away with self defense if I killed 3 gang members that jump me?

Maybe.

If the circumstance are such that your life was in danger, self defense is a valid defense. Sometimes a person may not even be charged wit the crime of murder if it happened under circumstances that the prosecutor is convinced that the act was in self defense.

Self-defense is very fact specific. Based on what you have provided, it is impossible to predict the outcome of a trial on the issue.

If you were attacked first, they had you outnumbered, and they were physically assaulting you, then you should be justified under the law using lethal force or potential lethal force to propel such an attack. The force you use has to be reasonable under the circumstances.

The technical term is homicide with justification. The answer is going to require a look at the totality of the circumstances i.e. the entire factual situation. The ultimate questions are whether the action that you took was reasonable under the circumstances, and whether you reasonably could had a fear for your life or of serious injury. You should anticipate having consideration given to where you were, why and what type of weapon you had (this may work to your benefit or detriment). Reasonable refers to a reasonable person standard and is not necessarily what you personally think is reasonable, which would be a subjective standard.

You should if it was self defense.