Although some have been rescued, others remain missing and at least 6 are dead.
The dramatic effort to find and rescue passengers on the sunken Korean ferry becomes more critical with each passing moment.
Chilling water temperatures, swift currents, and low visibility complicates efforts to locate victims and survivors. Although the exact number of passengers aboard is unclear, over 300 were high school students.
They were on their way to the resort island Jeju for a 4 day field trip. Rescued passengers report hearing a loud bump, then feeling the ship lift heavily.
Some say they ignored ship announcements warning them to stay in place, instead grabbing life jackets and heading to the deck.
The ferry sank within 2 hours of the first distress call.
"We had no idea what was happening. We thought everything was going to be okay and then this happened."
Officials say dozens have been rescued but many more are feared dead.
A United States Navy Ship on routine patrol in the area dispatched helicopters to assist. Cell phone video that appears to be shot from inside the sinking ship has emerged. It shows passengers waiting for help.
"It is possible that there are air pockets inside some of the compartments. The temperature of course, could lead to hypothermia quickly. The other thing to keep in mind is that once the ship goes on its side or flips over, it's tremendously disorienting. Everything is sideways or upside down."
On the mainland, frantic family members search a posted list of those that have already been rescued and continue a heart wrenching vigil for those who have not yet been found.
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