According to reports, a US-manufactured Sikorsky S-92 helicopter that carried four crew member fell in the waters 370 kilometres (230 miles) southwest of Mara on Friday at 13:32 (04:32 GMT). The crash happened shortly after the helicopter took off on its way to Busan.
"Following the helicopter's crash, the patrol boat's crew rescued three people and two of them died, while the remaining one remains missing," a coast guard official was quoted as saying by the news agency.
The new outlet noted that currently 17 vessels, including a navy warship, coast guard boats and private fishing boats, are searching for the missing crew member.