one involves your home. Some parents allow their kids to throw parties and drink when parties are there. But what happens when your teen throws a party and someone tweets about it or puts up a... See More
one involves your home. Some parents allow their kids to throw parties and drink when parties are there. But what happens when your teen throws a party and someone tweets about it or puts up a facebook post, hundreds might show up. Tonight, gio benitez at the front door with police, the new party crashers. Reporter: Remember in the movie "mean girls" when lindsay lohan threw a party for a few of her closest friends? I don't know you. Reporter: Whom she had never met. Noore than ever, "a few friends," takes on a whole new meaning. Seems miley was right on the money. ♪ Party in the usa ♪ Reporter: Coast to coast, parties have been going viral and spiraling out of control. Fueled by facebook, infused by instagram and turbocharged by twitter. In colorado, when a few students gathered for a little pool party they texted their friends, and they texted their friends. And in no time -- this is the biggest party I've seen in my entire life. Reporter: News of the party made a splash on the internet, and so did 500 kids. I didn't think it would get that big. Reporter: As the booze started flowing, the pool started overflowing, police showed up, and made four arrests. 10 partiers were taken to the hospital. In a boston suburb, jill abbott's 18-year-old son was staying with a neighbor when they were on a vacation in paris. When he went home to feed the cat, police say a few classmates barged into the house, then went on facebook to announce a party. One of them put on facebook, call or text rager, for details this number. Reporter: A hundred teens showed up and caused $40,000 in damage. They urinated in every single drawer in my house. Reporter: But sometimes, it can go from disgusting, to deadly. In houston, texas, an invitation went viral on facebook and twitter, almost 1,000 people showed up at this empty mansion. When police were called to break it up, one partier started shooting, one was dead. So, how do you put a fire like this out? Well, you look for the smoke signals, online, and that's exactly what the los angeles county sheriff's department is doing, creating a specialized unit, the first and only one of its kind. Dedicated to watching parties in real time, through social media. Lieutenant rod armalin runs this unprecedented team. Like the cia that listens for terrorists chatter, this unit listens for dangerous party buzz, hoping to break up the bashes before they get really bad. We're on facebook, we're on instagram, we're on twitter, Reporter: And you're using search terms like "bring you own beer, party tonight, kick back tonight." Its new age data mining with e-vites in hand. All these are all twitter parties. It looks like we got six locations, and we're going to six parties. Reporter: Acting on tips from twitter and facebook, the unit rolls out and we are along for the ride. First stop is advertised on facebook as a birthday party. Like, many this invite boasts goodies. Code for pot, pills. And the latest party drug of choice, nitrous oxide. The gas that you get in a dentist office known as noz. We arrive with the team at 8:44. So this is the party that say massive backyard on this facebook post. Officers are in there right now checking it out. Seeing what's in there, who's in there. We found a couple of tanks back there. They basically fill the balloons with the gas, and a balloon will sell anywhere from 5 bucks to 10 bucks a balloon. And then the kids inhale the gas out of the balloons. Reporter: You can feel the air escape the party when mom comes home and the lieutenant wants to talk. They didn't want to show their faces on national television. You have two empty nitrous oxide tanks, you have balloons, and I am telling you that we would be making arrests. Yeah, I know. If those tanks were full. This has to stop, this can't go on. Reporter: The night is still young. The team is ready to party on. Tipped off by social media, the team drops in. Nothing's a bigger buzz kill than a bunch of cops. 10:52, the lieutenant and his team arrive, partiers disperse, leaving a trail of evidence. Bottles, jello shots, and a noz tank. The police say they were selling these jello shots to minors inside that party. And it looks like the homeowners are coming here right now, and it looks like the party patrol is getting ready to talk to them. They are having a party in the back? Yeah, yeah. They are selling nitrous oxide and -- no, no, no. Reporter: She doesn't understand why what she thought was to be a small gathering, turned out to be a bash with much more than booze. The officers are telling her that there's nitrous oxide inside this party and she's saying, no, there's no way. I didn't believe it. That he showed the flier. Reporter: The flier, and that's when you said, what it's on the internet. Yes. He showed that that tank was Reporter: And your address was on there for everyone to see. They could still come by, right? Reporter: You might see some more people walking by. Oh my goodness. Reporter: Even some of the kids cant believe the party was online. It was on the internet. Reporter: This party? Last stop for the night, call it new age event planning. An invite for a blowout at a zumba studio. These kids paying admission to be out of their parents purview for the night. But they couldn't escape the long arm of lieutenant armalin and his posse. The lieutenant and his unit walked in, didn't like what they saw inside and kicked every body out. As partiers streamed out, they left behind remnants of the night. Beer cans, balloons and those noz tanks. Party hosts maria and kimberly underestimated the power of social media. Did you expect it to get this big? Um, no. We didn't expect it. Because it was like 500 people? It was? Oh, my god. Reporter: And we saw that in each one of these parties so many people were there because they saw it on social media. I mean, effective they invite the entire world, if they choose to. Reporter: Now, lieutenant armalin has an instant message for parents, property owners and party promoters. We need the parents to be educated on this. They had no idea that their children were using social media to get the attention of the world about this party they're throwing.
This transcript has been automatically generated and may not be 100% accurate.