Several non-credible bomb threats that briefly disrupted voting at two Georgia polling places originated from Russia, Georgia Secretary of State Brad Raffensperger told reporters Tuesday.

“We’ve heard some threats that were of Russian origin. I don’t know how to describe that that’s viable – we don’t think they are, but in the interest of public safety, we always check that out, and we’ll just continue to be very responsible when we hear about stuff like that,” Raffensperger said. “We identified the source, and it was from Russia.”

“They’re up to mischief, it seems, and they don’t want us to have a smooth, fair and accurate election,” he added. “Anything that can get us to fight amongst ourselves - they can count that as a victory.”

Raffensperger, a Republican, did not elaborate on how exactly state officials determined the bomb threats came from Russia.

The non-credible threats caused the temporary closure of polling places at the Etris Community Center and Gullatt Elementary in Union City, just outside of Atlanta, according to Fulton County Police. Union City’s population is nearly 90% Black, according to the US Census Bureau.

The county is seeking to extend voting hours due to the disturbance, according to Nadine Williams, Fulton County registration and elections director.

An FBI statement said it was aware of the threats but did not address their source.

“Election integrity and protecting our community is our highest priority, and the FBI is working closely with state and local law enforcement partners to respond to election threats and protect our communities as Americans exercise their right to vote,” the FBI said in a statement.

The statement said the bureau has no information to indicate the threat is credible.

One voter, Michael Osborne, said he believed something was wrong the moment he pulled up to his Union City polling site Tuesday morning and spotted EMS and police vehicles around the building. An officer told him and other voters they couldn’t enter the site to vote because of a bomb threat.

“They had to remove all the workers, they couldn’t let anyone in until they assessed the threats,” said Osborne.

Osborne said the delay at the Etris Community Center was roughly an hour, and voters were forced to wait outside until law enforcement officers cleared the building.

“Three voters were mid-vote when it happened and probably about 25 people in line,” said poll watcher Evette Reyes.

CNN’s Isabel Rosales, Mounira Elsamra and Denise Royal contributed to this report.