Officials also offered a rare glimpse at their investigations, saying they were looking into whether a crewman's order to abruptly turn the ship contributed to the 6,852-ton Sewol ferry tilting severely to the side and filling with water Wednesday.
The confirmed death toll from the sinking off southern South Korea was 28, the coast guard said. Most of the bodies have been found floating in the ocean because divers have been continually prevented from getting inside the ship by strong currents and bad weather. But more than 48 hours after the sinking the number of deaths was expected to rise sharply with about 270 people missing, many of them high school students on a class trip. Officials said there were 179 survivors.
New questions were raised by a transcript of a ship-to-shore exchange and interviews by The Associated Press that showed the captain delayed the evacuation for half an hour after a South Korean transportation official told the ship it might have to evacuate.
The comment at 9 a.m. by an unidentified official at the Jeju Vessel Traffic Services Center came just five minutes after a distress call by the Sewol ferry. A crewmember on the ferry, which was bound for Jeju island, replied that "it's hard for people to move."
The captain has not spoken publicly about his decision making; officials continue interviews him and the crew. Earlier, a crewmember told the AP that the captain's eventual evacuation order came at least half an hour after the 9 a.m. distress signal.
Meanwhile, strong currents and rain made rescue attempts difficult again as the search for possible survivors entered a third day. Divers worked in shifts to try to get into the sunken vessel, where most of the missing passengers are thought to be trapped, said coast guard spokesman Kim Jae-in.
Coast guard officials said divers began pumping air into the ship Friday in an attempt to sustain any survivors.
South Korean officials also offered some information about what may have led to the sinking. They said the accident happened at a point where the ferry from Incheon to Jeju had to make a turn. Prosecutor Park Jae-eok said in a briefing that investigators were looking at whether the third mate ordered a turn whose degree was so sharp that it caused the ship to list.
Park said that officials were looking at other possible causes, too. South Korea's Yonhap news agency reported that the third mate was a 26-year-old with a year of experience steering ships and five months on the Sewol.
The ship made a sharp turn between 8:48 a.m. and 8:49 a.m. Korea time, but it's not known whether the turn was made voluntarily or because of some external factor, Nam Jae-heon, a director for public relations at the Maritime Ministry, said Friday.
Park also said crews' testimonies differed about where the captain was when the ship started listing. As that listing continued, the captain was "near" the bridge, Park said, but he couldn't say exactly where.
Near the site of the ferry, angry and bewildered relatives who had gathered on a nearby island watched the rescue attempts. Some held a Buddhist prayer ritual, crying and praying for their relatives' safe return.
"I want to jump into the water with them," said Park Geum-san, 59, the great-aunt of another missing student, Park Ye-ji. "My loved one is under the water and it's raining. Anger is not enough."
Kim, the coast guard spokesman, said three vessels with cranes arrived and would help with the rescue and to salvage the ferry, which sank not far from the southern city of Mokpo. But salvage operations hadn't started yet because of the rescue attempts.
Of the 29 crewmembers, 20, including the captain, Lee Joon-seok, 68, survived, the coast guard said.
The captain made a brief, videotaped appearance, although his face was hidden by a gray hoodie. "I am really sorry and deeply ashamed," Lee said. "I don't know what to say."
Kim Soo-hyun, a senior coast guard official, said officials were investigating whether the captain got on one of the first rescue boats.
The 146-meter (480-foot) Sewol had left Incheon on the northwestern coast of South Korea on Tuesday for the overnight journey to the southern resort island of Jeju. There were 475 people aboard, including 325 students from Danwon High School in Ansan, which is near Seoul,
It was three hours from its destination Wednesday morning when it began to list for an unknown reason.
Prosecutors on Friday raided the offices of the ship's owner, Chonghaejin Marine Co. Ltd, in Incheon.
The operator of the ferry added more cabin rooms to three floors after its 2012 purchase the ship, which was built in Japan in 1994, an official at the private Korean Register of Shipping told the AP on Friday.
The official, who spoke on condition of anonymity because the person was not allowed to discuss matters under investigation, said the extension work between October 2012 and February 2013 increased the Sewol's weight by 187 tons and added enough room for 117 more people. The Sewol had a capacity of 921 when it sank.
As is common in South Korea, the ship's owner, Chonghaejin Marine Co. Ltd, paid for a safety check by the Korean Register of Shipping, the official said, which found that the Sewol passed all safety tests, including whether the ship could stabilize in the event of tilting to the right or to the left after adding more weight.
Ian Winkle, a British naval architect and ferry expert said many ships have such modifications, to increase capacity, for instance.
Oh Yong-seok, a helmsman on the ferry with 10 years of shipping experience, told AP that when the crew gathered on the bridge and sent a distress call, the ship was already listing more than 5 degrees, the critical angle at which a vessel can be brought back to even keel.
The first instructions from the captain were for passengers to put on life jackets and stay where they were, Oh said.
A third mate reported that the ship could not be righted, and the captain ordered another attempt, which also failed, Oh said. A crew member then tried to reach a lifeboat but fell because the vessel was tilting, prompting the first mate to suggest to the captain that he order an evacuation, Oh said.
About 30 minutes after passengers were told to stay in place, the captain finally gave the order to evacuate, Oh said, adding that he wasn't sure in the confusion and chaos on the bridge if the order was relayed to the passengers. Several survivors told the AP that they never heard any evacuation order.
By then, it was impossible for crew members to move to passengers' rooms to help them because the ship was tilted at an impossibly acute angle, said Oh, who escaped with other crewmembers. The delay in evacuation also likely prevented lifeboats from being deployed.
The last major ferry disaster in South Korea was in 1993, when 292 people were killed.