"Sunday morning, the authorities responsible for the enforcement of the act we have contacted about activities that they have recently discovered and who, could they be related to foreign entities", says the press release.
The blog posted late Monday said, in part, "Our very early-stage investigation has so far identified around 30 Facebook accounts and 85 Instagram accounts that may be engaged in coordinated inauthentic behavior".
The social media company shut down dozens of Facebook and Instagram accounts and is investigating them in more detail. The accounts on Instagram were mainly in English, some "focused on celebrities, others on the political debate".
"But given that we are only one day away from important elections in the USA, we wanted to let people know about the action we've taken and the facts as we know them today".
Facebook didn't always take the risk of election interference seriously, however.
The announcement came shortly after U.S. law enforcement and intelligence agencies said that Americans should be wary of Russian attempts to spread fake news.
Trump to reporter: 'You are a bad person'
He also asked about the Russian investigation. "You shouldn't be working for CNN", Mr. You shouldn't be working for CNN. "I consider it to be an invasion", Trump responded.
A spokesperson for Facebook declined to disclose any other details about the extent of the current investigation, including which USA law enforcement agency tipped off Facebook.
'Foreign actors - and Russian Federation in particular - continue to try to influence public sentiment and over perceptions through actions meant to sow discord, ' the agencies said.
The company chose to announce its actions right away, "given that we are only one day away from important elections in the USA", he said.
Facebook said it needed to do further analysis to determine whether the accounts it deleted are linked to Russian Federation or the Internet Research Agency, both of which were accused of being involved in past election-meddling efforts.
"The American public can mitigate these efforts by remaining informed, reporting suspicious activity, and being vigilant consumers of information", the statement said.
"It is increasingly clear that major gaps exist in Facebook's efforts, potentially allowing adversaries to exploit your platform with continued disinformation efforts", the senators wrote in a letter Zuckerberg, PC Magazine reported.