An attempt to illegally obtain absentee ballots in Florida last year is the first known case in the U.S. of a cyberattack against an online election system, according to an NBC News report.

The case involved more than 2,500 “phantom requests” for absentee ballots, apparently sent to the Miami-Dade County elections website using a computer program. It is currently unknown if the requests were an attempt to influence a specific race, test the system or interfere with voting. But the number of requests – plus the fact that most were sent from a small number of IP addresses in Ireland, England and India – software used by the county flagged them for rejection, the article says.

Computer experts say that the case exposes the danger of putting states’ voting systems online, whether merely registering or actually voting.

While experts contacted by NBC News agree that the attempt is the first known case of cyberattacks on voting, there are so many local elections systems in use that it’s possible a similar attempt has gone unnoticed.

The full report is available here.