Hackers attempted to access national campaign finance systems a week before the midterms.

Hackers attempted to access some Federal Election Commission file systems, prompting the independent campaign finance regulator to shut them down Tuesday to contain the attack, a person familiar with the matter told POLITICO.

According to this person, who requested anonymity to discuss details of an ongoing internal investigation, the FEC’s cybersecurity staff “noticed intrusion attempts and were able to shut down” the parts of its electronic filing system that were under attack, leading to what they described as a temporary outage.

“It’s pretty narrow and compartmentalized,” the person said of the hack attempt. “The team noticed this early on and we hope to have this resolved shortly.”

Reuters first reported on Tuesday that hackers targeted the FEC, citing an email sent by the FEC about the incident. Some agency systems remain down Tuesday evening.