MOKPO, South Korea -- Twenty people have been confirmed dead in Wednesday's sinking of a ferry off South Korea's coast, but the number is expected to go much higher.
More than 270 passengers are missing, many of them high school students. The search for the missing has been hampered today by strong, dangerous currents, rain and bad visibility. Officials say divers will continue through the night to try to enter the ship, hoping for gentler currents.
PHOTOS: Hundreds still missing in Korea ferry disaster
A coast guard official in South Korea says investigators are looking into whether the captain of the sunken ferry got on the first rescue boat at the scene.
The captain was among the crew members who survived the sinking, which may have killed nearly 300 people. A crew member says as the ship started to list, there was no immediate order for passengers to evacuate, because officers were still trying to stabilize the vessel.
More than 400 rescuers searched nearby waters overnight and into Thursday morning. Poor visibility and strong currents are hampering the effort. The coast guard says currents have prevented drivers from getting into the wreckage.
The ship had set sail from Incheon, a city in the northern part of the country and the site of South Korea's main international airport, on Tuesday night for an overnight, 14-hour journey to the tourist island of Jeju.
About three hours from its destination, the ferry sent a distress call at about 9 a.m. local time Wednesday after it began listing to one side, according to the Ministry of Security and Public Administration. Officials didn't know what caused it to sink, and said the focus was still on rescuing survivors.
Lee Gyeong-og, a vice minister for South Korea's Public Administration and Security Ministry, said 30 crew members, 325 high school students, 15 school teachers and 89 non-student passengers were aboard the ship.