Facebook said it blocked 115 Facebook and Instagram accounts believed to be engaging in manipulation ahead of today’s midterm elections after receiving a tip from federal law enforcement officials who suspected the activity was linked to foreign entities.

The company said its early investigation identified about 30 Facebook accounts and 85 Instagram accounts engaged in “coordinated inauthentic behavior.”

“Typically, we would be further along with our analysis before announcing anything publicly,” said Nathaniel Gleicher, Facebook’s head of cybersecurity policy, in a blog post published Monday. “But given that we are only one day away from important elections in the U.S., we wanted to let people know about the action we’ve taken and the facts as we know them today.”

At this early stage, Facebook says it doesn’t know which foreign actors were attempting to spread mischief on its platform, or whether any of these accounts are linked to the Russia-based Internet Research Agency.

All the Facebook pages associated these accounts appear to be in the French or Russian languages. The Instagram accounts are mostly in English — some were focused on celebrities, others political debate, Gleicher wrote.

The company has taken steps to curtail manipulation of its platforms after being widely criticized for allowing Russian trolls spread misinformation during the 2016 election.

Facebook established a “war room” in its Menlo Park headquarters, staffed with a team focused on identifying misinformation, monitoring false news and deleting fake accounts that might be trying to influence voters.

Just last week, the company removed 82 pages and accounts on Facebook and Instagram that were part of a coordinated effort to fan tensions around politically charged topics such as race relations, opposition to the president and immigration.

One of these pages had attracted at least 1 million followers, Facebook said in a blog post.

Facebook is not alone in grappling with the problem. Twitter removed some 10,000 automated accounts posting messages that tried to discourage and dissuade voters from casting ballots in the midterm election.