SEOUL (Yonhap) -- Vote counting began for Wednesday's local elections, with exit polls showing the ruling and main opposition parties each winning five of the 17 metropolitan mayoral and gubernatorial posts up for grabs, while running neck-and-neck in the other races.

Voting took place from 6 a.m. to 6 p.m. at 13,665 polling stations nationwide, drawing 56.8 percent of eligible voters, according to a preliminary count by the National Election Commission (NEC). The turnout was the highest for nationwide local elections since the first such polls in 1995 when it reached 68.4 percent.

Ballot boxes were sealed as soon as voting closed and taken to 252 counting offices for counting.

The first nationwide elections in 18 months were seen as a referendum on President Park Geun-hye's conservative administration amid public anger over the government's botched handling of a deadly ferry sinking in April.

Winners are expected to emerge around 11 p.m., although the results for closely contested constituencies could come out early Thursday morning.

The election was held to choose a total of 3,952 officials, including 17 metropolitan mayors and provincial governors, and 226 heads of low-level administrative units.

Some 41.29 million people, or 80.4 percent of the country's population of 51.33 million, were eligible to vote, according to the NEC.