Voting to conclude at 8 pm local time (1100GMT), final results expected early Wednesday
South Koreans headed to the polls Tuesday in a snap election being held to pick a new leader, months after President Yoon Suk Yeol was removed from office for declaring martial law.
Polling stations opened at 6 am local time (2100GMT Monday) and will close at 8 p.m. (1100GMT).
Millions of citizens are expected to participate in the day-long voting to choose a new president who will serve a one-time five-year term.
Nearly 29,000 police officers have been deployed across the country, where people will cast their ballots at around 14,295 polling stations.
As of 11 am local time (0200GMT), turnout was recorded at 18.2% and over 8 million voters have cast their ballots, said the National Election Commission.
The early election was triggered by the Dec. 14 impeachment of former President Yoon following his failed attempt to impose martial law on Dec. 3.
Polling was due within two months after South Korea's Constitutional Court upheld the National Assembly's impeachment of Yoon in April.
He was supposed to serve as president until 2027.
Yoon along with his wife, Kim Keon Hee, also cast their votes at a polling station in the capital Seoul.
More than 15 million out of a total 44.3 million eligible voters including overseas South Koreans have already cast their ballots in the two-day early voting period.
Surveys show that Lee Jae-myung, representing the main opposition Democratic Party, is leading the presidential race with close to 50% support.
Lee lost to Yoon in 2022 by a thin margin.
Kim Moon-soo from the ruling People Power Party is trailing Lee with nearly 37% support.
Besides the two frontrunners, there are three other candidates in the race: Lee Jun-seok of the New Reform Party, Kwon Young-guk from the Democratic Labor Party and an independent contender, Song Jin-ho.
This is the 21st presidential election in the country since its establishment in 1948.
The successful candidate will be sworn in soon after his victory is confirmed as early as Wednesday morning.
Lee Ju-ho, the deputy prime minister and education minister, became acting president last month after the resignations of Prime Minister Han Duck-soo and Finance Minister Choi Sang-mok.
This time South Korea will not see a transition period of 60 days, and instead the new leader will quickly begin his term, with fresh policy decisions expected on issues including US tariffs, the sluggish domestic economy and all-time low ties with North Korea.
