Facebook made an “operational mistake” this week in failing to remove a page that encouraged armed Americans to take to the streets of Kenosha, Wisc., CEO Mark Zuckerberg said. The page clearly violated Facebook\n \n (FB)’s rules against violent militias, Zuckerberg acknowledged in a video posted Friday to his Facebook\n \n (FB) profile, and that “a bunch of people” had even reported the page prior to the killing of two protesters, Joseph Rosenbaum and Anthony Huber. Just last week, Facebook announced it would crack down on militia organizations that advocated for violence or spoke about the potential for violence. But in its first week of implementation, the policy’s lack of enforcement led to the spread of violent messages on the platform directly linked to the events in Kenosha, where protests erupted after the police shooting of Jacob Blake. “What’s going on in Kenosha … is really deeply troubling,” Zuckerberg said in the video. BuzzFeed News was first to report Zuckerberg’s remarks, before he posted the video. A Facebook investigation of the militia page turned up no evidence that the page or the event it promoted had any connection to the 17-year-old accused of committing the killings, Zuckerberg said. But the Facebook contractors who received the initial reports from users about the militia page did not “pick it up,” he said. “On second review, doing it more sensitively, the team that’s responsible for dangerous organizations recognized this violated the policies, and we took it down,” Zuckerberg said. Following a report by BuzzFeed News, Facebook later acknowledged that while it removed the militia page, it failed to remove the event being promoted by the group. “When we responded to questions about our initial investigation into what happened in Kenosha, we believed we’d removed the Event Page for violating our policies,” Facebook said in a statement. “Our investigation found that while we did remove the Kenosha Guard Page, the Event was removed by the organizer. We apologize for the error.” Before it was taken down, the event page on Facebook had received at least 2,600 responses and had caught the attention of at least one right-wing conspiracy website. Zuckerberg said Facebook is now “proactively out there looking for content” that praises the shooting. “We’re going to continue to enforce our policies,” he said, “and continue evolving the policies to be able to identify more potential dangerous organizations, and improve our execution in order to keep on getting ahead of this.” This story was updated the week after it was initially published to reflect Facebook’s acknowledgement that it had not been behind the event’s removal.