A ship carrying 459 people fell on its side Wednesday off South Korea's southern coast. Four are dead and almost 300 are missing.

Many on the ship were high school students. Parents of the teens are eagerly awaiting news of their children.

The high school students from the Seoul area were headed to Jeju island for a field trip.

At about 9 a.m. local time Wednesday, the ship sent a distress call because it was leaning to one side according to the Ministry of Security and Public Administration. The government also said that about 95 percent of the ferry is submerged.

Coast guard officers say the reason for the ferry's sinking is unknown. Throughout the day, estimates of the missing on the ferry have increased.

Emergency workers tended to the students, most of them wet and wrapped in blankets. One student, Lim Hyung-min told interviewers that he and fellow students grabbed life jackets and jumped into the ocean before swimming to a rescue boat nearby.

"As the ferry was shaking and tilting, we all tripped and bumped into each another," Lim said, adding that some people were bleeding. Once he jumped, the ocean "was so cold. ... I was hurrying, thinking that I wanted to live." 

Those who jumped or fell into the ocean faced water temperatures of about 54 Fahrenheit which is cold enough to cause hypothermia after about 90 minutes.

The ship sunk several miles north of Byeongpung Island near the mainland and almost 300 miles from Seoul, the coast guard said.

Another passenger, Kim Seong-mok told YTN that he feared many people were trapped inside the ferry still and because of the sharp angle of the tilt of the ship, they couldn't reach exits. 

Kim felt the ferry tilt and heard it hit something. He also said that the ferry operator made an announcement asking passengers to stay where they were.

The trip from where the students departed, Incheon port, to Jeju island takes about 14 hours. The ferry was about three hours away from Jeju when it made its distress call.

As word got out about the ferry to students at the high school in Ansan city, many began to cry and worry. Teachers tried to comfort these students and assure them that their classmates would be fine.

There are many different groups of divers, government boats and coast guard teams assisting with the rescue and search efforts officials said.

If the death toll rises, this could be one of the worst ferry disasters in South Korea since 1993 when 292 died in the Yellow Sea.