SEOUL, South Korea (AP) —  Hundreds of people are missing and at least two are confirmed dead after a ferry carrying 477 passengers, many of them students, sank in cold waters off South Korea’s southern coast Wednesday.

There were fears of a big jump in the number of deaths, as dozens of boats, helicopters and divers scrambled to rescue passengers who had been on the ferry travelling to the southern island of Jeju. At least two people are confirmed dead, but officials say about 295 people are unaccounted for. One survivor says he believes that many people were trapped inside the ferry when it sank.  The confirmed fatalities are a female crew member, 22, and a male student.

The water temperature in the area was about 55 degrees Fahrenheit, cold enough to cause signs of hypothermia after about 90 minutes or 2 hours, according to an emergency official who spoke on condition of anonymity citing department rules.

Photographs show the partially submerged ferry tilting dramatically as helicopters flew overhead and rescue vessels and a small boat covered with an orange tarp over it floated nearby.

The male student who died was in a group of 338 students and teachers from Danwon High School in Ansan, near Seoul, who were on a field trip.