The Facebook video starts from the perspective of the driver’s seat of a truck, peering out the windshield at night. It’s pitch black. A few seconds in, a man’s voice snaps, “They’re going up the road.” The engine starts, and headlights flash on to reveal a line of people hunched over, darting across the dirt carrying children. The camera, which appears to be from a smartphone, keeps rolling as the man filming grabs a bigger flashlight and runs out of his truck toward a woman kneeling on the ground holding a crying child, dousing the two in bright light. He brings them, with four more women carrying their young children, to sit on the dirt to wait for U.S. Customs and Border Patrol. As of Monday morning, this video has been removed (or set to private).

The narrator introduces himself as Jim Benvie, a field reporter with Build the Wall and a member of the United Constitutional Patriots, an armed right-wing militia that patrols the U.S.-Mexico border. The group has been coordinating with Border Patrol agents to capture families and individuals fleeing extreme poverty and violence, mostly from Central America, with the hopes of seeking asylum in the U.S. The night the video described above was shot, the group helped apprehend dozens of people who had been fleeing Guatemala. The American Civil Liberties Union of New Mexico has called the activities of the United Constitutional Patriots “unlawful arrests,” adding that the vigilante members of the group “have no authority under New Mexico or federal law to detain or arrest migrants in the United States.” On Saturday the leader of the UCP, Larry Mitchell Hopkins—who went by the alias Johnny Horton Jr.—was arrested on charges of possessing firearms as a felon.

“We’re down here live every day, 24/7 on the U.S.-New Mexico border. And we are basically watching the border, assisting Border Patrol, basically filling in the gap where they can’t. This is an invasion, guys. It is a crisis, and I want to show you what’s going on here,” Benvie said in the Facebook video for Build the Wall. It’s unclear how long the group has been operating, but Benvie told the New York Times he’s been camped near El Paso, which sits on the border of Mexico, New Mexico, and Texas for the past two months. (The UCP Facebook page was created in 2016.) Debbie Collins Farnsworth, one of the group’s active members, has been sharing videos on Facebook of men with assault rifles walking along the border for at least the past five months. Her videos of the United Constitutional Patriots patrolling and arresting people seeking asylum have amassed hundreds of thousands of views. Without Facebook, it’s unlikely that the group would court nearly as much attention, which helps the militia raise money.

Without Facebook, it’s unlikely that the group would court nearly as much attention, which helps the militia raise money.

Facebook’s viewing platform encourages users to host a “Watch Party,” with members of a group watching a video together with a dedicated comment space. Benvie and Farnsworth air many of their videos live, which often prompts Facebook to send followers a notification, further boosting awareness and spread of the video. This, according to Joan Donovan, director of the Technology and Social Change Research Project at Harvard Kennedy’s Shorenstein Center, helps the militia grow its audience. “If every member of that audience had to remember every time they wanted to go to a website, there would be very low traffic on a bunch of different fringe websites,” says Donovan. “But because the audience is centralized and can be ticketed into the event or pulled in through an alert, the mechanism by which social media produces the audience is an enormous advantage then just trying to produce or promote content on your own.”

The videos have the feel of a live-action police chase, similar to the show Cops. They’re frequently supplemented by thousands of comments from onlookers encouraging and thanking the armed militia members for patrolling the border. “We know the truth Jim!! You guys are true patriots!! They are looking for any excuse to shut you down!! Don’t let the fake news win!!” wrote one viewer on a Facebook video Benvie posted Friday, mirroring hundreds of other comments on the same video praising his militia work. Others have inquired how they can join, and one person posted an email address for people to reach out to about joining another independent border patrol group.

After the New York Times reported on the group’s activities last Thursday, PayPal and GoFundMe stopped servicing them. Still, there’s evidence that similar extremist militia groups have used Facebook itself as a donation platform—the Mountain Minutemen’s leader, Robert Crooks, was able to fundraise $1,600 on the site just last month. Another armed militia group, the Three Percent United Patriots, maintains a Facebook group with more than 19,700 followers and still solicits donations via PayPal. Even as fundraising sites stop servicing them, Facebook offers a centralized way for supporters to communicate in private messages. Those who wish to support the United Constitutional Patriots can easily send a note to ask how to best send funds.

Facebook has a policy against allowing organizations that are engaged in violence or organized hate from having a presence on the social media site, but the company didn’t immediately respond when reached for comment. “Facebook allowing these groups to persist and allowing them to be promoted within their system means the company shares in the culpability of whatever ends up happening to the people who are kidnapped,” said Donovan.

Update, April 23, 2019: A Facebook spokesperson said, “People cannot use our fundraising tools for activities involving weapons. We will remove fundraisers this group may try to start on our service and any content that violates our Community Standards.”

Future Tense is a partnership of Slate, New America, and Arizona State University that examines emerging technologies, public policy, and society.