(CNN) The FBI is investigating after someone allegedly tried to hack into West Virginia's mobile voting app during the 2018 midterm elections.

One or more people allegedly attempted to hack into Voatz, an experimental app that lets voters who are active military or registered to vote abroad cast their votes from their phones, Mike Stuart, the US attorney for the Southern District of West Virginia, announced Tuesday.

Stuart said in a statement that "there was no intrusion and the integrity of votes and the election system was not compromised," but that an investigation had begun, was "ongoing and no legal conclusions whatsoever have been made regarding the conduct of the activity or whether any federal laws were violated."

West Virginia is the only state that currently allows for the system, though it's been used and is being considered in several cities and counties across the country.

"We just noticed a certain group of people from a certain part of the country tried to access the system. We stopped them, caught them and reported them to the authorities," Voatz co-founder and CEO Nimit Sawhney told CNN.

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