Apparently, our stock photo provider isn't big on "sh*tfaced teens" as a category.
If I were still a teenager, this would be the lamest story ever. Since I'm not, however, it's absolutely delightful:
A couple from Glastonbury, Connecticut went away for the weekend, leaving their 15 and 16-year-old daughters at home. You've already figured out the next part: they invited their friends over and successfully had small parties on Friday and Saturday night (15-20 people). The parents weren't supposed to be home until Monday, though, so naturally the girls decided to go for a hat trick and throw three get-togethers in one weekend.
What the kids forgot, though, is that mommy and daddy can't bear to be away from their little poopsiekins for too long. So, if the itinerary calls for a Monday morning return, there is always a 50/50 chance they'll just decide to come home late Sunday night because they're worried about you. For good reason.
As you've deduced, the parents drove up to find Party 3 going strong. Pretty much all the kids who were there that evening escaped via the time-honored "run into the woods" strategy, but that didn't stop the parents from calling the police on their daughters and having them arrested for allowing minors to possess alcohol.
The parents called it "the right thing to do." Every teen for a 100-mile radius called it "super weak." Everyone who hates teenagers (everyone who is not a teenager) called it "schadenfreude."