JINDO, South Korea, April 20 -- Death toll of a sunken South Korean ferry rose rapidly Sunday as divers kept entering the hull of the submerged vessel while hundreds of ships were scouring the waters.

As of 1:30 p.m. local time, two more bodies were found in waters near the site of the accident, raising the death toll to 52, according to the pan-government emergency management headquarters which has been coordinating rescue efforts.

Four more bodies were discovered and retrieved from inside the hull and the waters, local media reported citing the South Koran Coast Guard.

So far 56 people have been confirmed dead, and 246 still missing. The number of rescued remained unchanged at 174.

A senior coast guard official told reporters during the morning briefing that five underwater ropes, which guide divers through rapid currents to the underwater gate of the ferry from surface, have been installed and the ropes enabled divers to go down into the sunken vessel at a much faster pace than before.

Coast guard, navy and private divers have been entering the hull through their separate guidelines simultaneously, the official said, noting it resulted in random discovery and retrieval of bodies trapped inside the hull.

More than 560 divers conducted search operations into the hull overnight 15 times, with 192 rescue ships and 31 airplanes mobilized.

One body was found at 7:10 p.m. Saturday by the coast guard vessel in waters near the site of the accident as the divers had difficulties in going into the hull.

Three bodies were retrieved at 11:48 p.m. from the passenger compartment on the fourth floor of the five-story ship after the divers broke open the window glass and entered the cabin. It was the first recovery inside the hull nearly four days after the 6, 825-ton ferry capsized and sank off Jindo Island, the southwestern tip of South Korea.

At 5:35 a.m. Sunday, one more body was retrieved from the cabin, and 15 minutes later three more bodies were collected. Nine more bodies were retrieved from the hull from 7:40 to 8:02 a.m.

A total of 563 divers will enter the hull through the five guidelines to search more bodies and possible survivors, while 204 rescue ships and 34 aircraft will scour the areas near the vessel.

The ship Sewol departed the western port city of Incheon Tuesday night for the southern resort island of Jeju. Among the 476 passengers and crew were 325 high school students and 15 teachers on a four-day field trip.

Divers have striven against rapid currents to get into the hull of the ship, and found three bodies with the naked eye for the first time on Saturday morning.

The third and fourth floors are composed of passenger cabins, where most of possible survivors may be trapped. There are freight compartments on the second floor and a dining room on the first floor. Divers succeeded in reaching the first and second floors Friday.

Around 87 passengers stayed at the cabins on the third floor, with 353 put up on the fourth floor and seven on the fifth floor.