A passenger ship carrying more than 470 people has sunk off South Korea's southern coast and a massive rescue operation is under way.
Officials say at least one person has been found dead. So far, at least 147 people have been rescued from the ferry.
South Korean television showed the boat leaning heavily to one side, and then slowly sinking, almost completely under the water.
South Korean Vice Minister of Security and Public Information Lee Gyeong-og says President Park Geun-hye has made the rescue a top priority.
"Eighteen helicopters were mobilized for the rescue work with (a) firefighting team, coast guard, navy, and police forces. Thirty-four vessels from the coast guard and 25 from the navy were mobilized, as well.
A team of South Korean navy SEALS are also participating in the rescue.
The reason for the crash is not clear. Some passengers reported hearing a loud noise before the ferry started sinking.
Most of the passengers were high school students headed to the popular resort island of Jeju on a school outing.
The students attend a school in Ansan, near Seoul. Classes were dismissed Wednesday as anxious parents gathered, waiting for news about their children.
The ferry departed late Tuesday from the western port of Incheon. It sank about 20 kilometers off the island of Byungpoong.
Heavy fog was reported in the area on Tuesday evening, but it is not known whether this contributed to the sinking.