Illinois Secretary of State Jesse White

CHICAGO (AP) — Illinois election officials say at least three of 16 voters who cast ballots after being mistakenly registered to vote are U.S. citizens after all.

Illinois Secretary of State Jesse White’s office blames an error in Illinois’ automatic voter registration system for over 500 people who self-identified as noncitizens being wrongly registered to vote.

The State Board of Elections has said 16 of those individuals voted in elections in 2018 and 2019. Spokesman Matt Dietrich said Wednesday that three are now confirmed as U.S. citizens and another two could be as well.

Republicans have called for the program to be suspended.