SEOUL, April 18 -- South Korean coast guard and navy divers, who entered into the hull of the sunken South Korean passenger ferry earlier Friday, have withdrawn from the submerged ship as the entrance into cabin was jammed with too many goods. No survivor has been reported yet.

Two divers made their way into compartments on the second floor of the five-story ferry at 3.38 p.m. local time for the first time Friday, two days after the ship carrying 475 people, mostly high school students, capsized off the country's southwestern coast.

The divers withdrew from the hull 14 minutes after going near the gate of the freight compartment as too many goods blocked the entrance into the cabin, local broadcaster YTN reported, quoting the South Korean Coast Guard.

The second floor is comprised of freight compartments and there is a dining room on the first floor.

Possible survivors were believed to be trapped on the third and fourth floors where divers can reach only after completing the work of pumping air into the first and second floors. After that, search and rescue operations will begin.

Maritime police and military divers tried 20 times overnight to make their way into the submerged hull, but they failed due to rapid currents, low underwater visibility and high waves.

The divers succeeded in entering the hull for the first time Friday morning but didn't find any survivor.

Death toll has kept rising, with 28 people confirmed dead and 268 others still missing. The number of the rescued has been unchanged at 179.

Passengers aboard the sunken vessel included 325 high school students and 15 teachers who had been on the way for a four-day field trip. The ship departed from South Korea's western port city of Incheon Tuesday night for the southern resort island of Jeju.

Among the rescued, 75 were students from the Danwon High School in Ansan, a Seoul suburb.

Three large salvage ships arrived at the scene Friday morning to pull the ship out of the waters, and another one got there in the evening. It was expected to take over one month to salvage the submerged vessel.

A total of 535 coast guard and navy divers were working at the scene, and 31 airplanes and 173 rescue ships were deployed for search and rescue operations.

The death toll could surge as hundreds of people were still missing two days after the 6,825-ton passenger ship, "Sewol," capsized and sank off Jindo Island near the southwestern tip of South Korea. Most of the missing were believed to be trapped inside the sunken vessel.

Two Chinese nationals were confirmed to have been aboard the sunken ferry, one male and the other female, on their way to Jeju Island for vacation.