Wouldn't want the kids to be killed - that's just an easy cop out. I think there'd be more satisfaction in knowing they were severly punished by other means though. And i mean proper punishment - not putting them up in some top of the range correction unit with video games and other luxuries, with the occasional day of picking up litter.
Kids these days are a lot more clued up at younger ages than people think. Whether or not it was their upbringing that turned them into such vermin, they still need to understand that
every action you make has a consequence.
And what about the 8 year old girl? How fucked up would she turn out to be knowing her attackers only got a slap on the wrist?! Obviously the kids weren't that naive if they were capable enough to do that to her...this wasn't an impulsive act like pulling her pigtails or stealing her dinner money, but something far more calculated and twisted that would have required some level of understanding in order to follow it through. Sorry but it'd be extremly naive to think they didn't know exactly what they were doing.
The boys should be punished severely regardless. They need that bit of fear instilled in them to understand the severity of their offence. This country spends so much frigging time wrapping children up in cotton wool to the point were they can't even be disciplined anymore without the fear of the adult in charge being accused of child abuse. It's pathetic.
As for the parents of the boys - best start would be to have them neutered like animals to stop them from infesting the world further if they're going to be so bloody irresponsible. There's just no excuse for them.
Killing them would be too kind...