Numerous Facebook pages in support of Bernie Sanders’ presidential candidacy were shut down on Monday after they were reportedly flooded with pornographic images, with at least one participant in the attacks being linked to a Hillary Clinton support group.

The incidents, which The Hill stated seemed to be coordinated, began around 9:00pm on Monday, with account owners being able to regain control of their groups around midnight. According to a report from Heavy.com, attackers posted porn in at least two groups and then reported the content to Facebook, triggering the shutdowns.

Some of the groups that were shut down had tens of thousands of members, including: Bernie Sanders Is My Hero, Bernie Believers, Bernie Sanders for President, and Bernie Sanders Activists.

Not all Bernie Sanders groups reported being hit with obscene imagery, but one member said it appeared that child porn was also posted.

"We had what looked like a kiddie porn posted in one of our groups today,” said Sanders supporter Erica Libenow said to Heavy.com. "I reported that one. Seriously made me want to vomit.”

On Twitter, Sanders supporters pointed to Clinton supporters as the culprits.

In a Facebook post on Tuesday, the Bros 4 Hillary group said that a former member was part of the attack, engaging in “harassing behavior” toward the pro-Sanders groups.

“This was not promoted or supported by the leadership of B4H, nor were we immediately aware of this conduct. We removed the offending posts and member as soon as possible,” the group wrote in its statement.

Some have also tried to connect the onslaught to Correct the Record, a Super PAC supporting Clinton that recently announced it would spend $1 million to target online attacks against the former secretary of state. According to Paste, one Facebook user bragged that he was able to get a Sanders group removed, and the user also “liked” Correct the Record and the Barrier Breakers' online “correction” initiative.

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However, the Super PAC denied that it took part in Monday’s attack.

"Correct the Record's Barrier Breakers 2016 had nothing to do with this," said Elizabeth Shappell, the group's communications director, to The Hill. "Currently, Barrier Breakers is exclusively engaged in positive messaging supporting Hillary Clinton."

Not all the shutdowns were linked to Clinton supporters, though. In one post, The People for Bernie Sanders 2016 group stated that a Facebook error was responsible for the shutdowns.

“We're aware many of the pro Bernie groups were removed from Facebook. They're back. It was a Facebook database error, not a conspiracy or an attack,” the statement read.

Other Facebook groups unrelated to Sanders were also briefly taken down.

Accusations over Monday’s Facebook incident are the latest in the back-and-forth between Clinton and Sanders supports. The Clinton campaign has often criticized the Sanders campaign for its so-called “Bernie Bros,” or outspoken supporters who have attacked those who disagree with Sanders online. Some have been labeled misogynist for suggesting that Clinton voters are voting “based on who had the vagina.”

For his part, Sanders has said the attacks are “disgusting” and called for his supporters to stop.

“We don’t want that crap,” he said to CNN in February. “Anybody who is supporting me [that] is doing sexist things – we don’t want them. I don’t want them.”