When a death list with the names of 69 people first surfaced on Facebook, authorities dismissed it as a joke.
But now that three Colombian teenagers included on the list have been killed, local reports say federal officials are taking a closer look.
In the past 10 days, Diego Ferney Jaramillo, 16; Eibart Munoz Alejandro Ruiz, 17; and Norbey Alexander Vargas, 19; were all killed in the small town of Puerto Asis in Putumayo, Colombia. The names of those three teenagers, as well as the names of 66 others, were listed in a message posted to Facebook earlier this month.
Diego Ferney and Alejandro Ruiz were shot and killed Aug. 15 while riding a motorcycle on a road between the towns Puerto Asis and Puerto Caicedo, and Alexander Vargas was killed Aug. 20, CNN said.
According to the Colombian paper El Espacio, the Facebook message, which the paper said is now blocked, warned families to leave the area or face consequences.
"Please, as a family, urge them to leave town in less than three days, otherwise we will be obligated to realize acts such as those of August 15," it said.
The Colombian ombudsman Volmar Perez Ortiz issued an "early warning," calling on the youth protection authorities and an investigation, the paper said.
The ombudsman's alert also said the Los Rastrojos gang is present in some towns of Puerto Asis and "executes violent acts, spawning community conflicts, imposing their will, intimidating and dispensing punishment against those culturally and socially stigmatized" and threatening community leaders, merchants and cab drivers.
Other reports say the warning mentioned that the Revolutionary Armed Forces of Colombia, or FARC, also operates in the area.
When contacted by ABCNews.com, a Facebook spokesman said, "We take users' security very seriously, and reached out to local law enforcement as soon as we became aware of the issue in Colombia."
Police have not said who is responsible for the killings or the online death list but are investigating the matter.
"It is still not clear," Colombian national police spokesman Wilson Baquero told CNN. "This is part of the investigation."
Vanda Felbab-Brown, an expert in illicit economies and Colombia at the nonprofit Brookings Institution, said the Facebook death list is reminiscent of the hit lists distributed by the paramilitary groups that terrorized Colombia in the 1980s and 1990s.
"Los Rostrojos is one of the groups that emerged out of the supposedly demobilized paramilitaries," she said. "The paramilitary groups, which had a long history, going back the 1960s, that fought the FARC, fought the leftist guerillas, were independent drug runners, independent drug trafficking organizations. For a long time, they colluded with the Colombian government and they were the source of some of the most vicious, bloody massacres and killings."
The paramilitary groups were demoblized in 2005 but splintered off into what the government now calls criminal gangs.