The FBI discovered evidence that foreign hackers might have penetrated two state election databases, according to a report from Yahoo News.

While the FBI bulletin that reported the breach did not identify the states, sources familiar with the document told Yahoo News that voter registration databases in Arizona and Illinois were targeted.

[DCCC Hacked in Series of Cyberattacks Against Democratic Groups]

Illinois was forced to shut down the state’s voter registration system for 10 days in late July after hackers downloaded the personal data of up to 200,000 voters.

Homeland Security Secretary Jeh Johnson convened a conference call earlier this month with state election officials and offered his department’s assistance in making voting systems more secure, including providing cybersecurity expertise in looking for vulnerabilities, according to the report.