Goose Creek voters had to cast paper ballots in Tuesday's municipal election after an unknown error message popped up on 12 voting machines.
Berkeley County elections director Adam Hammons said the voting machines malfunctioned when the first voter showed up as polls opened at 7 a.m.
When election officials discovered the error, Hammons said they immediately switched to paper ballots and notified state election officials.
"This is the exact same equipment we use every election. This is not something we have seen previously," Hammons said of the malfunctioning voting machines.
Until the issue can be resolved, Hammons said Goose Creek residents will be casting their ballots for a new mayor and three council members on paper.
On a paper ballot, voters fill in their choices similar to the way students would bubble in their answers on a Scantron sheet.
Hammons said the switch to paper could slow down their ballot counting tonight after polls close at 7 p.m.
"We have to read in the paper ballots just like we read in the paper ballots for our absentee ballots. They will be run through the ballot scanner. They will not be hand-counted. There will be no hanging chad," he said.
It is routine for county election officials to test election equipment 3-4 weeks before an election, Hammons said.
When Berkeley County election officials tested three voting machines ahead of Tuesday's election, Hammons said they did not encounter any errors.
State Election Commission spokesman Chris Whitmire said Tuesday afternoon that the investigation into what happened was ongoing, but officials had determined the technical hiccup was not a hardware failure. He estimated that voting machines in Berkeley County were back up and running after 2:30 p.m.
"It appears to be some type of human error in the preparation of the voting machines for the election. We still don't know exactly what the issue or cause was but, again, we are doing our due diligence to determine that," Whitmire said. "There's no indication whatsoever of any sort of hack or outside penetration of the system."
The voting machine glitch comes at a time when states nationwide are reassessing the security of their voting systems.
State election officials said there were nearly 150,000 unsuccessful attempts to gain access to South Carolina's voting system during the 2016 presidential election.
The State Election Commission has asked state lawmakers for $20 million in the 2018-19 budget to replace the state's voting system, along with another $4 million for ongoing maintenance for the state's current system. The governor's proposed budget suggested allocating $10 million for a new statewide voting system.
"This is a concern for all of us in the election community and it's something that we pay attention to. I feel like everything we do on our end is to make sure that our equipment is secure," Hammons said. "Sometimes, though, with electronic equipment there are just failures."
Hammons said he hopes the post-election audit process will help them decipher exactly what happened.