Fundraisers, messages of support and celebratory memes for the alleged Kenosha, Wisconsin, mass shooter are being shared widely on Facebook and Instagram, despite the company’s assurance on Wednesday that it was working to enforce its policy banning content that “praises, supports, or represents” mass shooters.

One fundraiser for Kyle Rittenhouse, 17, was shared more than 17,700 times on Facebook, including by 291 public groups and pages with more than 3.9m aggregate followers, according to data from CrowdTangle, a Facebook-owned data analytics tool. A second fundraiser garnered 1,698 shares on the platform, including by an additional 17 pages and groups with nearly 400,000 followers.

Rittenhouse was arrested on Wednesday and charged with first degree intentional homicide in connection with the fatal shooting at a Black Lives Matter protest in Kenosha late Tuesday night. The deceased victims have been identified as Anthony Huber, 26, and Joseph Rosenbaum, 36. A third victim, Gaige Grosskreutz, 26, was wounded and is expected to survive.

Facebook designated the shooting a “mass shooting” – a ruling that invokes the company’s ban on praise, support, or representation of a mass shooter or the shooting itself, a spokesperson said on Wednesday. And yet those types of posts continue to be spread widely on the platform, according to a Guardian analysis of CrowdTangle data.

Hundreds of Facebook posts and memes featuring the phrase “Free Kyle” or “Free Kyle Rittenhouse” had garnered more than 70,000 interactions as of Thursday morning. Many of the posts include stills captured from videos of Rittenhouse carrying his assault rifle before, during and after the shooting. One meme posted on Wednesday afternoon by the page “All About Trump 2020”, which has more than 32,000 followers, shows Rittenhouse with his arm raised in the air and includes the caption, “3 commies down”.

Dozens of similar “Free Kyle” memes were also attracting significant support and engagement on Instagram, where they had been liked nearly 60,000 times. The Instagram hashtags #KyleRittenhouseIsAHero and #KyleRittenhouseDidNothingWrong revealed hundreds of pro-shooter memes and posts.

The fundraisers that were shared on Facebook were removed by the fundraising platforms they were started on, Fundly and GoFundMe respectively, but many posts sharing the link alongside messages of support for Rittenhouse remain live on Facebook. The fundraisers were largely shared by groups and pages with pro-Donald Trump, anti-Joe Biden, and pro-gun or militia themes. One notable group that shared it was one of Facebook’s largest anti-vaccine groups.

CrowdTangle only includes data from public pages and groups, so the analysis does not account for content that may be spreading in private groups or among individual users.

Some of those sharing pro-Rittenhouse content appeared aware of Facebook’s ban on content that praises or supports mass shooters. Some users are attempting to blur the wording in their memes to evade Facebook’s AI systems; others are using the threat of censorship to inspire more dissemination of the pro-shooter material.

On Thursday morning, Joshua Feuerstein, an Evangelical Christian social media influencer best known for a viral video in which he complained about Starbucks’ red holiday cups, shared a meme showing a photo of Rittenhouse during the shooting with the slogan, “I stand with Kyle Rittenhouse”. “SHARE THIS BEFORE THEY TAKE IT DOWN AGAIN!” Feuerstein wrote to his 2.6 million fans. His fans responded, sharing the image more than 3,700 times over about two hours before the image was removed.

Facebook is facing increased scrutiny over the use of its platform by groups threatening or intending to commit violence. A newly formed local militia called Kenosha Guard used Facebook to organize an event for “Armed citizens to protect our lives and property” in Kenosha on the night of the shooting. It is not yet clear if Rittenhouse responded to the Facebook “call to arms”, which was also amplified by the conspiracy site InfoWars.

Following the shooting, Facebook removed the Kenosha Guard page and its event for violating its new policy against US-based militias with links to violence. Two Facebook users told tech news site The Verge that they had reported the page and the event invitation to Facebook before the shooting, out of concerns that violence would occur, only to have Facebook moderators say that the pages did not violate any rules.

“What happened in Kenosha was preventable but Facebook chose to look the other way yet again,” said Madihha Ahussain, Muslim Advocates’ special counsel for anti-Muslim bigotry. “Before any more people are threatened by armed bigots and any more lives are lost, Facebook must finally take responsibility for the horror it continues to enable and stop militias and hate groups from using its platforms to organize hate.”

Henry Fernandez, a senior fellow at the Center for American Progress, said: “Facebook must ensure that its event pages will not be used to kill people. If it cannot do so, then it should get out of the events page business.”

Facebook did not immediately respond to multiple requests for comment. Brian Fishman, Facebook’s head of counter-terrorism and dangerous organizations, said in a Twitter thread that the company was “still scaling up enforcement” on its new policy against militias and other groups linked to violence. Fishman also said that the alleged shooter’s accounts had not been reported by anyone before the shooting, and that the company had not found any evidence to suggest Rittenhouse followed the militia page or was invited to the event.

He added: “We’ve had too many tragedies like those in Kenosha. Companies like Facebook owe it to everyone to closely examine the influence of online content on such violence – and to take action to stop it.”

The social media company’s efforts to crack down on the posts supporting Rittenhouse are probably complicated by the behavior of the rightwing media. The Fox News host Tucker Carlson justified Rittenhouse’s actions on Wednesday, though he stopped short of praising the alleged murderer. Facebook has long been sensitive to complaints of anti-conservative bias from Republican politicians and rightwing publications. If the American right adopts Rittenhouse as a cause célèbre, Facebook may be forced to pick sides.