Police arrested rapper Colson Baker, also known as Machine Gun Kelly, when he refused to get off a table during a flash mob event at a mall in Ohio.
In late September, law enforcement officials from around the country will gather in Dallas to discuss how to manage social media.
One huge challenge is how to deal with flash crowds gone bad: groups of people who use social networks to gather and do something illegal.
These kinds of crowds are a problem that local police departments are just starting to figure out.
'This Was Going To Be A Problem'
In what sounds like an Internet tall tale, a teenager recently posted an online invite for a water fight and wet T-shirt party at a park in the Cleveland suburb of South Euclid. Instead of the 50 responses the teen was expecting, more than 2,700 said they were coming.
Usually the kid would cancel the party, but in this case the teen and his friends promoted it on Twitter.
For South Euclid Police Chief Kevin Nietert, this was a real headache.
"It'd be akin to a snowball rolling downhill, really," he says. "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."
While teens have always looked for ways to gather and have fun, Nietert argues that 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 K-9 teams. Not surprisingly, party plans quickly fizzled.
"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," Nietert says.
Often, so-called flash mobs gather to raise awareness for a cause or to stage a dance routine or to just have fun, but seemingly everywhere this summer were images of youth responding to online calls to cause havoc.
Lauri Stevens, a social media strategist for law enforcement, estimates that no more than 15 percent of the country's 18,000 law enforcement agencies are actively using or monitoring social media.
"I think that law enforcement is really struggling with the rapidity with which social media has come into the forefront of communications," she says. "And now, on top of that, these flash mobs are really taking a lot of law enforcement by surprise."
A New Kind Of Police Beat
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 Sept. 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 "flash mob" with him at a local mall.
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 after police arrest rapper Colson Baker, also known as Machine Gun Kelly, when he refuses to get off a table.
Strongsville Police Chief Charles Goss says that 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 we're trying to do exactly same thing — get that word on the street," Goss says. "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 are 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.