Facebook has banned a large group called "Stop the Steal" that Donald Trump supporters were using to organise protests against the presidential vote count.
Some members had called for violence, while many falsely claimed that Democrats are "stealing" the election from Republicans.
Though the group amassed more than 350,000 members before Facebook took it down, it was just one of several smaller groups that popped up as vote counting extended for days in several battleground states.
Inside the groups, members and organisers tried to ensure they would get around Facebook's moderators and "trolls" who might report or mock them.
"In line with the exceptional measures that we are taking during this period of heightened tension, we have removed the Group 'Stop the Steal,' which was creating real-world events," Facebook said in a statement.
"The group was organised around the delegitimisation of the election process, and we saw worrying calls for violence from some members of the group."
Facebook said it will continue to watch for activity that violates its rules and will take action if it does. As of Thursday afternoon, a copycat "Stop the Steal" group was growing steadily, nearing 13,000 members, and others were easily searchable on Facebook.
Inside the groups, members posted baseless claims of voter fraud and organised protests. Calls for violence were not immediately apparent, although the Centre for Countering Digital Hate shared a screenshot of one post in the now-banned group that read "Neither side is going to concede. Time to clean the guns, time to hit the streets."
In the new group, administrators - who create and moderate groups on Facebook, cautioned people to keep posts civil and vent frustrations without making threats.
They scrupulously warned members that they will remove anything that calls for violence, and said they were making plans to move the group to other, less-moderated platforms.
Imran Ahmed, CEO of the Centre for Countering Digital Hate, which pressured Facebook to take down the group, said while it's true that all this seems like a game of whack-a-mole, the moles are slowly learning their lesson.
"By taking out the largest one, it sent a message to others," he said.
Ahmed said Facebook continues to fail to take action and it did so only when a lot of attention was placed on something.