UPDATE: 10:47 p.m.
SEOUL, South Korea (CNN, MyNews4.com & KRNV) -- Rescue boats and helicopters scrambled to pluck hundreds of passengers, most of them high school students, from a passenger ferry as it listed and slow sank off the southwest coast of South Korea on Wednesday.
Of the 474 people on board, 368 were rescued, many from the freezing waters into which they had jumped from the listing ship.
At least two people are confirmed dead, and 104 remain unaccounted for, South Korean officials said.
The rescue operation was still underway at 2 p.m. local time (1 a.m. ET), four hours after the ferry first sent out distress signal.
Authorities could not immediately say what caused the ship to sink. The weather at the time of the incident in the area was clear.
Update: 9:35 p.m.
SEOUL, South Korea (CNN, MyNews4.com & KRNV) -- At least one person died when a South Korean ferry sunk off the country's southwestern coast, CNN affiliate YTN has reported.
In total there were 447 passengers and 27 crew on the ferry, a total of 474 people. Among the passengers, around 320 were students.
The Coast Guard has confirmed that there is at least one death, as a female body has been recovered.
The South Korean Ministry of Security and Public Administration has confirmed that 179 passengers have been rescued.
One parent told YTN that her child was safe, and was with 11 others. All of them jumped into water and were rescued by a ship. Of the 11, one suffered a fractured leg, but the remainder were reportedly uninjured.
One student, resting at the Jindo Indoor Auditorium with other rescued passengers, told YTN that he heard a loud bump, which was quickly followed by the ship beginning to sink.
"I had to swim a bit to get to the boat to be rescued," student Lim Hyung Min told YTN. "The water was so cold and I wanted to live. I think most of the students are now rescued. I have 20 other students with me and many of us suffered from hypothermia but now we are OK because we got blankets."
Original: 7:00 p.m.
SEOUL, South Korea (AP) -- A government office says a South Korean passenger ship carrying about 470 people has sent a distress call off the southern coast after it began leaning to one side.
South Korean media, including Yonhap news agency, say passengers were asked to jump overboard with life vests as the ship was on the verge of sinking. News reports say about 120 people have already been rescued.
The Busan Regional Maritime Affairs & Port Administration says in a statement that the ferry with 471 people was sailing to the southern island of Jeju when it sent a distress call Wednesday morning.
There are no immediate reports of causalities.
Agency officials say they have no further details. Calls to South Korea's coast guard headquarters weren't immediately answered.