MELISSA BLOCK, Host:
Here in the U.S., law enforcement officials are gathering later this month to discuss social media. It's an issue some police departments are just starting to confront. One huge challenge is flash mobs gone bad when groups of people get together and do something illegal.
From member station WCPN in Cleveland, Mhari Saito reports on efforts to manage social media.
MHARI SAITO: Here's a story that sounds like one of those Internet tall tales. A teenager posts an online invite for a water fight and wet T-shirt party in a park. Instead of the 50 responses the teen was expecting, more than 2,700 say they're coming. Usually at this point in the story, the kid cancels the party. But in this case, the teen and his friends promoted it on Twitter.
For Kevin Nietert, police chief of the Cleveland suburb of South Euclid where the water fight was scheduled this summer, this was a real headache.
KEVIN NIETERT: It'd be akin to a snowball rolling down hill, really. And we realized pretty quickly that this was going to be a problem. And we also realized pretty quickly that it was going to overwhelm our resources if in fact it took place.
SAITO: While teens have always looked for ways to gather and have fun, Nietert argues these kids had a history of making trouble in crowds. Nietert claims the organizers of the water fight had also promoted flash crowds in the neighboring town of Cleveland Heights that had led to fights, arrests and some property damage.
So on the day of the water fight, Nietert closed the park listed on the invite and scheduled a training session there for about 15 police K9 teams. Not surprisingly, party plans quickly fizzled.
NIETERT: Just as our procedures in responding to domestic terrorism or responding to child abductions have evolved over years through experience and learning, this is one of those things that's going to evolve too.
SAITO: Often, so-called flash mobs gather to raise awareness for a cause or to stage a dance routine or to just have fun. Lauri Stevens is a social media strategist for law enforcement. She estimates that no more than 15 percent of the country's 18,000 law enforcement agencies are actively using or monitoring social media.
LAURI STEVENS: I think that law enforcement is really struggling with the rapidity with which social media has come into the forefront of communications. And now on top of that, this flash mob is really taking a lot of law enforcement by surprise.
SAITO: But that's starting to change. Last month, the New York Police Department opened a social media unit to help track down criminals. Cities like Philadelphia and Milwaukee have imposed curfews to deal with flash crowds. In Cleveland, an agency that was set up to look for terrorists after 9/11 is now also monitoring potential illegal flash crowd activity. The Northeast Ohio Regional Fusion Center warned South Euclid police of the water fight invite. Police in Strongsville, Ohio also got a heads up that a rapper asked fans to, quote, "flash mob" with him at a local mall.
(SOUNDBITE OF MOB)
SAITO: In a YouTube video, more than 200 fans scream as the musician and his entourage walk into the packed food court. The crowd quickly leaves, though, after police arrest Colson Baker also known as Machine Gun Kelly when he refuses to get off a table. Strongsville Police Chief Charles Goss says these days his officers have to know what's happening online to do their jobs.
Like the cop on the beat used to have to get to know his shop owners by actually walking the beat and talking to them. And he got the word on the street by doing that. And now, were trying to do exactly the same thing - get that word on the street - but it follows a completely different electronic medium.
Goss says most of the teens who showed up at the mall and at many of these sort of flash events believe they're harmless. The worry for police at these kind of flash gatherings, he says, is when large crowds take on a mob mentality and their actions break the law. For NPR News, I'm Mhari Saito in Cleveland.