FRANKLIN, Ind. (AP) — A state agency is investigating an Election Day technical glitch that left some central Indiana voters waiting in lines for hours and others not voting at all.

Indiana Secretary of State Connie Lawson said Tuesday in a statement that her office is investigating Johnson County’s problematic electronic poll books and hopes “to determine the root cause of the problem.”

The (Franklin) Daily Journal reports that the poll books that are used to check in voters before they cast a ballot kept freezing on Nov. 6, stalling several voting machines and preventing some people from voting in the county just south of Indianapolis.

Lawson’s spokeswoman, Valerie Warycha, says the state agency has asked Ball State’s Voting System Technical Oversight Program to review the equipment provided by the county’s election vendor, ES&S.