By Tony Hanson

PHILADELPHIA (CBS) — Trial is underway in Philadelphia in a case in which three of seven teens packed inside a car were killed and one other was wounded when a man opened fire on them.

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The defense concedes the defendant is the shooter but says it was justified.

Prosecutor Jude Conroy today told the jury there had been an ongoing feud between groups of teens that included fights and threats, and says that defendant Axel Barreto’s stepson was a member of one of these groups.

On the night of the shooting, according to Conroy, the carload of teens went to Barreto’s block in that Juniata neighborhood, looking for a fight based on a Facebook challenge (see related story).

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Then, as they circled the block in a Toyota Corolla on that January 2012 night, Axel Barreto came out with a gun and opened fire on the car.

Defense attorney Jack McMahon told the jury that the victims’ group, whom he characterized as gang members, had engaged in months of threats and beatings, and when the carload of teens circled his block Baretto’s family was fearful and crying.

McMahon says Baretto went outside to protect his family, but when he circled a corner he was startled as the car moved forward and he fired, out of fear and panic.

McMahon says the shooting was justified.   The case is continuing.

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