Four people are dead after a ferry with hundreds of passengers sank off the coast of South Korea on Wednesday morning. At least 300 passengers are still missing.  

The ferry Sewol was carrying 475 passengers to a resort on the South Korean island of Jeju. A distress call was sent out at 9 a.m., local time, when the ferry began leaning to one side, Fox News reported. Reports say the multiple-level ferry sank with alarming speed.

Of the passengers, most of whom were high school students, 164 were rescued, and 55 suffered injuries. Dive teams are still searching the waters for the remaining 292 passengers that are still missing, CNN reported.  

The four dead include a female crew member and male high school student, according to Kang Byung-kyu, a government minister, Fox News reported. There is no confirmation yet on the other two bodies, but one is believed to be that of a student.

One student who survived told broadcaster YTN that he put on a life jacket, jumped into the water and swam to a rescue boat, according to Fox News.

"As the ferry was shaking and tilting, we all tripped and bumped into each other," Lim Hyung-min said. The water was "so cold...I was hurrying, thinking that I wanted to live."

Officials do not yet know what caused the ferry to sink. Because the ship sank so fast, the vessel most likely sustained "major damage," Peter Boynton, a former U.S. Coast Guard captain, told CNN. Boynton also said that a rupture in the ferry's car deck could have caused rapid flooding.

The students, from Danwon High School near Seoul, were traveling to Jeju for a four-day trip, Fox News reported. The island is a favorable destination for South Korean high schools organizing trips for freshman and sophomore students.

The ship was built in Japan in 1994 and can carry up to 921 passengers, Yonhap news agency reported, according to Fox News.