In one of the videos, two handcuffed men speaking Spanish admit to being narcotics smugglers before being beheaded with a chainsaw and a knife. In another, a woman in a pink tanktop is decapitated by a masked man, who holds her severed head aloft for the camera to see.
The videos appeared to have been deleted from Facebook on Thursday.
"We have decided to remove instances of this video -- and others like it, when they are reported to us," Facebook spokesman Alison Schumer told The Huffington Post in an email.
Schumer also said the company is still evaluating its policy on graphic content, which at the moment doesn't cover whether NSFW posts that have news value should be allowed on or banned from the site.
In its Community Guidelines, Facebook says that graphic imagery is allowed, except when it's posted "for sadistic pleasure" or might lead to someone being harmed. An internal guide for content moderators, obtained last year by Gawker, notes that images of decapitations should be deleted. But the guide is not part of Facebook's official policy and also notes that gory photos (of deep flesh wounds, for example) are acceptable as long as you can't see anyone's "insides" spilling out.
As recently as Tuesday, Facebook was defiantly refusing to delete the decapitation videos.
"Just as TV news programs often show upsetting images of atrocities, people can share upsetting videos on Facebook to raise awareness of actions or causes," Facebook Public Policy Associate Manager Fred Wolens told The Examiner at the time. "While this video is shocking, our approach is designed to preserve people's rights to describe, depict and comment on the world in which we live."
Facebook had come under fire for the videos from individual users and from an online petition calling on the social network to pull the videos.
"The question is, is Facebook a news site? You could make an argument [that such videos are in the public interest] on a mediated news site like The Huffington Post, like CNN or NBC.com, where you have professional editors and standards and you are accountable," Balkam said over the phone. "But the public interest argument becomes far more tenuous for Facebook, and also for Tumblr and for YouTube."
The videos' origins are hard to pin down. Nothing is known for certain about who made them or where they were filmed.
(Hat tip, BBC)