Story highlights The US has accused Russia of attempting to influence the US election with hacking

It has not yet accused Russia of targeting specific state election systems

(CNN) Federal investigators believe Russian hackers were behind cyberattacks on a contractor for Florida's election system that may have exposed the personal data of Florida voters, according to US officials briefed on the probe.

The hack of the Florida contractor comes on the heels of hacks in Illinois, in which personal data of tens of thousands of voters may have been stolen, and one in Arizona, in which investigators now believe the data of voters was likely exposed.

The FBI, in the coming days, is preparing to provide updated guidance to state elections officials around the US aiming to help them spot suspicious activity on their computer networks. Several states have reported attempted scans of their computer systems, which often is a precursor to a breach.

Previously, Illinois officials have said data on fewer than 90,000 people may have been affected by a breach there, and Arizona officials said they saw no indications hackers accessed data in their systems.

The vendor hack in Florida prompted the FBI last week to coordinate an emergency call with county election supervisors who operate the election system in the perennial battleground state. CNN has not confirmed the name of the vendor that suffered the attack.

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