A 53-year-old diver died Tuesday while making his first dive at the scene of the ill-fated South Korean ferry, becoming the first fatality in the grim and dangerous task of retrieving bodies from the sunken ship.

Lee Gwang-Wook allegedly suffered breathing difficulty upon reaching a depth of 25 meters. He lost consciousness and was pronounced dead in the hospital, said Ko Myung-Suk, a spokesman for the South Korean coast guard.

Like Us on Facebook

It was Lee’s first dive as part of the hundreds of divers who have volunteered to continue searching and retrieving bodies from inside the hull of the sunken ferry. Five minutes in the water, Lee lost contact with surface controllers.

A rescue for the diver was launched until he was found unconscious. His hose was entangled with other lines, which could have triggered the cutting of air support, said a coast guard official.

While Lee became the first fatality in the ongoing search and retrieval operation, several divers were treated for decompression sickness and exhaustion since the operation started 20 days ago.

Death toll now stands at 263 while 39 people, mostly highschool students remain missing. The South Korean ferry, Sewol, was on its way to Jeju Island when it suddenly listed along the way and totally capsized.

Recent investigation showed that the vessel was allegedly overloaded with cargo while sailing towards Jeju. According to investigators, Sewol was carrying 580 tons of ballast water, which is only 37 percent of the legal requirement, in order to load more cargo so it can make more money. The overloading made the vessel unbalanced.

On Tuesday, South Korean President Park Geun-Hye issued another apology for the government’s failure to prevent the disaster. She also vowed to go after those who committed corruption and wrongdoing that resulted to the tragedy.

“As the president who should protect the lives of the people, I don’t know how to express my condolences to the bereaved families. I feel sorry and my heart is heavy with grief,” she said.

The sinking of Sewol is considered as one of the country’s worst peacetime disaster. Among the passengers of the vessel were 325 students from the same high school in Ansan city.