Two residents of a Topeka care facility were prevented from voting in the Tuesday primary election by a poll worker who didn’t understand the state’s voter identification law.

The Topeka Capital-Journal reports that Secretary of State Kris Kobach confirmed Thursday that some elderly residents of Brewster Place showed up to a polling place without I.D.s and were turned away without being issued provisional ballots, as required by law.

Shawnee County Election Commissioner Andrew Howell says three voters were affected and one was later able to vote. He has apologized to the other two and says the error was attributed to a poll worker.

Kobach spearheaded the ID law and a proof-of-citizenship requirement to register, saying the measures prevent voter impersonation and protect the state from “alien” voters.