– Visibility ‘very low’ –
Lee said divers, including a team of South Korean navy SEALS, were searching the submerged vessel.
“There is so much mud in the sea water and the visibility is very low,” he added.
The US 7th Fleet said an amphibious assault ship, the USS Bonhomme Richard which was on routine patrol west of the Korean peninsula, was being sent to help.
The ferry had sailed out of the western port of Incheon on Tuesday evening.
The cause of the accident was not immediately clear, although rescued passengers reported the ferry coming to a sudden, shuddering halt – indicating it may have run aground.
The weather was described as “fine” with moderate winds and sea swell.
“There was a really loud noise and then the boat immediately began to shift to one side,” said one rescued adult passenger, Kim Song-Muk.
“People were scrambling to get to the upper decks, but it was difficult with the deck slanted over,” Kim told the YTN news channel.
One local official, who had taken a boat to the site and arrived an hour after the distress signal was sent, said he was “very concerned” about those still missing.
“The ship was already almost totally submerged when I got there. A lot of people must have been trapped,” the official, who declined to be identified, told AFP by phone.
The water temperature was cold at around 12.6 degrees Celsius (55 Fahrenheit).