The writing was on the walls. The Rollin’ 20s, The Avenues, the Nutty Blocc Compton Crips — spelled out or abbreviated, in dark ink on fences and the sides of buildings. The aliases of their members would be similarly tagged, on conspicuous lists known as “roll calls.”These were the territorial markers of South Los Angeles’s notorious street gangs two decades ago.

Today, those same groups have taken their business off the concrete and onto the Internet. The city began experiencing the ripple effects of this 21st century strategy last week, as rumors swirled on social media about a gang violence movement dubbed #100days100nights, allegedly sparked by the death of a member of the Rollin’ 100s.

Several circulating posts warn residents in the area of impending violence, citing hearsay that rival gangs are competing to be the first to reach a hundred slayings.

The proliferation of the hashtag has coincided with a spike in gang violence, with seven shooting incidents, injuring 11 and killing one, in South Los Angeles this past weekend.

LAPD South Bureau Deputy Chief Bill Scott noted that while the department is closely monitoring online activity around #100days100nights, they are more concerned about the fear it has evoked from the community than with the possibility of an underlying threat. While the incidents over the weekend were gang-related, they aligned more with typical criminal acts than a movement that would involve “indiscriminate acts of violence” randomly targeting neighborhood residents.

“We are hearing that this is really not a valid posting,” Scott said. “This situation may just be a bunch of hype.” He clarified that the tactical alert issued Saturday night was in response to the spike in violence — common given the cyclical nature of gang activity — and not to the hashtag itself.

Legitimate threat or not, #100days100nights speaks to a larger trend of gangs with formerly notable street presences moving their feuds to the battlegrounds of Facebook, Twitter and Instagram.

“The classic L.A. street gang is no longer a ‘street’ gang,” said Sam Quinones, a former Los Angeles Times reporter who covered gangs in the area for 10 years. “I don’t believe it is technically correct to call them that now, because you don’t see them on the streets anymore.”

It’s a stark contrast to the criminal heyday of the ’80s and ’90s, when “the essence of the Los Angeles street gang was to be in the streets,” Quinones said. After all, the streets were where the gangs got their names: the Rollin’ 20s for a group occupying the blocks between 20th to 29th streets, the Rollin’ 30s for 30th to 39th streets and so on. A gang’s success was judged in part by the strength of its physical presence, demonstrated by members marking public walls with graffiti, huddling around parks and liquor stores and commandeering entire apartment complexes for their illicit gatherings.

Thanks to legal orders established to curb gang activity, these practices have become far more rare. In their place, gang members have taken up the nebulous arena of online interaction as a way to make their existence known without putting themselves at great risk of police detection.

[Former gang members remove tattoos to break from past]

The migration of gangs off the streets has allowed residents in historically beleaguered communities such as Compton and Watts to put down roots without the constant threat of being caught in crossfire. According to LAPD records, there has been 33 percent fewer gang-related homicides so far this year than there were at this time in 2008.

“Working class neighborhoods have always borne the brunt of these guys’ behavior,” Quinones said. “Now neighborhoods have room to breathe. People are thinking, ‘Maybe I can paint my fence. Maybe I can plant that tree.'”

Still, UCLA professor Jorja Leap cautioned not to underestimate the power of gangs who have gone “underground” — and online.

Internet anonymity not only offers gang members a shield against police scrutiny, but also allows them to spread their message beyond geographic confines, said Leap, whose anthropology research focuses on gangs in the area. With regards to monitoring behavior on these platforms, “We’re building the plane while we’re flying it.”