If you are with your friends and some people are shooting at you and you shoot back and shot the person who was shooting at you. It is considered self defense right? What are the consequences?

Self defense is just that a defense, you will be charged and perhaps have to stand trial and use self defense as your defense, you admit the shooting but say you were protecting yourself or others.

1. why are they shooting
2. where is it happening at
3. why do you have a gun and is it legal for you to have it and carry it.
4. did you have your gun out first and was there other threats done.

Example, two drug dealers fighting over the drug deal, one pulls gun and shoots, the other pulls his gun and kills the other. He will be charged with felony murder since it happened during the committing of a crime, there is no real self defense here.

Also who are the witnesses and will the DA and/or the jury believe it was self defense.

From the time of the first "shot" to the time of the shot that killed, could the person have escaped.

Chuck is correct, there is no black and white answer here. The full circumstances will determine if a) you are prosecuted, b0 brought to trial and c) convicted by a jury.