FBI Chief Responds to Concern Over Cyberthreats to US Election System Agency is working with states on "options" to avoid election cyber attacks.

 -- The FBI has responded to recent concerns about U.S. voting systems being targeted for cyberattacks as Election Day approaches, saying the agency takes the threat "very, very seriously" and is working to "equip the rest of our government with options."

FBI Director James Comey addressed the issue while speaking to government and private-industry experts attending the Symantec Government Symposium in Washington, D.C.

"We take very seriously any effort by any actor," he said, "to influence the conduct of affairs in our country, whether that's an election or something else."

His comments come one day after news surfaced about FBI warnings to the states that hackers had infiltrated one state board of election and targeted another.

Three days ago, Senate Minority Leader Harry Reid, D-Nev., sent a letter to Comey, expressing concern that "the threat of the Russian government tampering in our presidential election is more extensive than widely known and may include the intent to falsify official election results."

In late June an "unknown actor scanned a state's Board of Election website for vulnerabilities" and, after identifying a security gap, exploited the vulnerability to conduct a "data exfiltration," or unauthorized data transfer, the FBI said in a recent bulletin.

Earlier this month, hackers used the same vulnerability in an "attempted intrusion activities into another state’s Board of Election system," the FBI said.

The bulletin did not say who may be behind the cyberattacks or the attacker's or attackers' location. But many suspect Russian hackers are to blame.

In the recent cyberattacks, voter-related information was stolen from the Illinois election system, and hackers tried to access Arizona's system, according to Yahoo News, which first reported on the bulletin.

"The prospect of a hostile government actively seeking to undermine our free and fair elections represents one of the gravest threats to our democracy since the Cold War," Reid wrote in his Aug. 27 letter to Comey, adding that the FBI should "investigate this matter thoroughly."

Reid is not alone in his concerns over potential Election Day cybervulnerabilities.

Three weeks ago, the ranking member of the Senate Homeland Security Committee called on the federal government to examine its efforts to protect election systems and voting machines in the United States against similar attacks.

"Election security is critical, and a cyberattack by foreign actors on our election systems could compromise the integrity of our voting process," wrote Sen. Tom Carper, D-Del., in a letter to the Department of Homeland Security.

For months, the FBI has been investigating what appear to be coordinated cyberattacks on Democratic organizations — the most damaging so far being the hacking of the Democratic National Committee.

Not only did the hack apparently allow cyberoperatives to steal opposition research on Republican nominee Donald Trump, but many suspect it led to the theft of internal messages that showed efforts by DNC officials to undermine Democratic presidential candidate Bernie Sanders during the primary season.

After those damaging emails were publicly released by WikiLeaks, Florida Rep. Debbie Wasserman Schultz stepped down as the DNC's chairwoman.

Many suspect Russian hackers are also to blame for these cyberassaults on Democratic organizations.

At the symposium in Washington today, Comey said state-sponsored hackers from places like Russia, China, Iran and North Korea "are getting much more sophisticated [and] much more aggressive" in their online activities.

ABC News' Ali Rogin and Geneva Sands contributed to this report.