If you hav read the article they were at a party and when their curfew was approaching they were headed to one of the girls houses. There is no implication that the girsl were loose or promicious.
Yes I think you're right - I read the 2nd part too quickly. I was initially under the impression that the girls were voluntarily part of the gang activities. I'm still a little perplexed though - it was at best incredibly naive and at worst homicidally negligent to let girls walk home at midnight in gang territory.