U.S. federal law enforcement and security officials on the eve of Election Day in the United States said foreign players were attempting to plant doubts about the U.S. voting process, warning that the efforts risked inciting violence against election officials.

In a joint statement, the federal officials pointed to a recent article posted by “Russian players” alleging that U.S. officials in states hosting presidential elections were developing a plan to rig the election, as well as a video purportedly showing an interview with a man claiming election fraud in Arizona.

U.S. intelligence said it had determined that Russian-linked influence actors were “producing videos and creating false articles to undermine the legitimacy of the election, instill fear of the electoral process in voters, and indoctrinate Americans into thinking that they are using violence against each other because of political preferences,” the Office of the Director of National Intelligence, the FBI and the U.S. Cybersecurity and Infrastructure Protection Agency said in a statement.

“These attempts carry the risk of inciting violence, including against election officials,” the statement said.

According to Microsoft analysts, the Iranian players also “created fake news sites and posed as online activists in an attempt to sway voters to their side.”