A vice principal who was rescued from a sinking South Korean ferry of 475 passengers earlier this week was found dead hanging from a tree, police said on Friday.

Kang Min-gyu was traveling with hundreds of high school students on the ferry when it sank off the southern coast of South Korea on Wednesday, Reuters reported. The vice principle was one of 179 passengers rescued. But his death, an apparent suicide, comes as divers are still searching for the 268 passengers that are still missing. Twenty-eight passengers are confirmed dead.

Police say Kang, 52, hanged himself with his belt from a tree outside a gym in the port city of Jindo, where those rescued were taken. No suicide note was found. The vice principal had been reported missing on Thursday by a colleague, Reuters reported.

Most of the missing passengers are students from Danwon High School, located in Ansan, near Seoul. The school was traveling to the southern island resort of Jeju for a four-day trip. The search for the sunken ship continues, but hopes of finding any more survivors dwindle.

"When I first received the call telling me the news, at the time I still had hope," said Cho Kyung-mi, one of the many family members who gathered at the high school. Cho's 16-year-old nephew was on the ferry.

"And now it's all gone."

Investigators do not yet know what caused the ferry Sewol to tilt to the side and then sink with alarming speed on Wednesday morning.

However, an arrest warrant was issued Friday for the ship's captain, Lee Joon-seok. It is not clear where the captain was when the ferry started tilting, but he was not in the steering room.

"I'm not sure where the captain was before the accident," Oh Young-seok, one of the helmsmen on the ship, told Reuters. "However right after the accident, I saw him rushing back into the steering house ahead of me.

"He calmly asked by how much the ship was tilted, and tried to re-balance the ship." Oh told Reuters.

Arrest warrants were also issued for two other crew members on the ferry, CNN reported.