Facebook said it had taken down a rapidly growing group where supporters of US President Donald Trump posted misinformation and violent speech, and organised protests against the baseless claim that Democrats were stealing the election.
The group grew to more than 365,000 members in one day.
The Stop the Steal group, which called for "boots on the ground to protect the integrity of the vote", was adding 1,000 new members every 10 seconds on Thursday afternoon.
"The group was organised around the delegitimisation of the election process and we saw worrying calls for violence from some members of the group," a Facebook spokeswoman said.
She said the move was in line with measures Facebook was taking during "this period of heightened tension".
The group prepared for Facebook to take action, directing new members to an email sign-up page "in the event that social media censors this group".
A new group using the same name had more than 1,000 members.
Stop the Steal was run by the Trump action group Women for America First.
The non-profit organisation ran protests against Covid-19 restrictions and supported Mr Trump during his impeachment hearing.
"The left is trying to steal an election and social media is complicit," one of the Facebook group's administrators, Amy Kremer, said on Twitter. "This is outrageous."
Unfounded and debunked claims about the integrity of the US election have been spread on social media by Mr Trump and high-profile Republican accounts, and the hashtag #StopTheSteal has gained momentum.