A search operation is underway at the sea off Jeju Island Wednesday morning. (Korea Coast Guard)

Fourteen crew members from a capsized cargo ship off southeastern Jeju Island were rescued in a joint search operation involving multiple coast guards as of early afternoon on Wednesday.

Of the rescued people, nine remained unconscious as of 5:30 p.m. Wednesday, according to the Korea Coast Guard Region-Jeju, or the Jeju Coast Guard. Those rescued there were sent to Japan to get hospitalized, and Japanese authorities will take charge of investigating the cause of the accident, according to South Korea's national coast guard authority, the Korea Coast Guard.

The search for the remaining eight members of the 22 crew members -- 14 Chinese and eight from Myanmar -- was ongoing, operated jointly by the coast guards of Korea and Japan, as well as the Japanese Maritime Self-Defense Force as of press time.

The 6,551-metric-ton ship registered in Hong Kong reportedly sank about 150 kilometers off Seogwipo, Jeju Island. A strong wind warning was in effect on the seas off Jeju Island early Wednesday morning until 4 a.m.

The timber-carrying ship was first reported in distress at around 1:45 a.m. to the Jeju Coast Guard. Its crew notified the national post guard that they would abandon ship at around 2:41 a.m. The ship is thought to have sunk at around 3:07 a.m., according to the national post guard.

Winds of 16 meters per second, sea water temperature of 18.5 degrees Celsius and 4-meter waves were recorded at the location of the sinking at around 7 a.m. Wednesday.