All 15 people involved in navigating the South Korean ferry that sank and left 302 people dead or missing are now in custody after authorities on Saturday detained four more crew members, a prosecutor said.

Yang Jung-jin of the joint investigation team said two helmsmen and two members of the steering crew were taken in on preliminary arrest warrants issued late Friday. Eleven other crew members, including the captain, had been formally arrested earlier.

All are accused of negligence and of failing to help passengers in need as the ferry Sewol sank April 16. The captain initially told passengers to stay in their rooms and took half an hour to issue an evacuation order, by which time the ship was tilting too severely for many people to get out.

Ten days after the sinking, 187 bodies have been recovered and 115 people remain missing. Only 174 people survived, including 22 of the 29 crew members.

The seven crew members who have not been arrested or detained held non-marine jobs such as chef or steward, Yang said in a telephone interview from Mokpo, the southern city near the wreck site where prosecutors are based. A court hearing was being held to determine whether formal arrest warrants will be issued against the four crew members arrested Saturday.

Capt. Lee Joon-seok told reporters after his arrest that he withheld the evacuation order because rescuers had yet to arrive and he feared for passengers' safety in the cold water. Crew members have also defended their actions.

Helmsman Oh Yong-seok, one of those arrested Saturday, has said he and several crew members did their best to save people. He said that he and four crew members worked from nearby boats to smash windows on the sinking ferry, dragging six passengers stuck in cabins to safety.

Officials in charge of the search effort said Saturday that divers have reached two large rooms where many of the lost may lie dead, but the search had to be suspended because of bad weather. Currents were already strong Saturday morning, as they were in the first several days of the search, when divers struggled in vain even to get inside the submerged vessel.

“This morning (the divers) did a primary dive, but because of the strong current they were losing their masks, so we have stopped the dive for now,” Kim Jin-hwang, a South Korean navy official in charge of commanding the dive search, said in a briefing at Jindo. He said the search would resume once conditions improve, but it was unclear when that would happen.

The two rooms where searchers hope to find more of the missing soon are sleeping units designed for many people _ one in the stern and one in the bow. Fifty students from Danwon High School in Ansan were booked into one of them. Students from the city near Seoul make up more than 80 percent of the 302 people dead or missing; they had been on their way to the southern tourist island of Jeju.

Large objects toppled when the ferry tipped over and sank are believed to be keeping divers from reaching bodies in at least one of the rooms.

“Many structures ... all fell down as the ship listed, and now are all buried on the left side. Because of the weighty objects it was impossible to entirely search the room,” Kim said.

Families have been upset with the pace of the recovery effort, along with several miscommunications by the government and perceptions of insensitivity. The government also been accused of rejecting help it should have accepted, such as a diving bell that civilian volunteer Lee Jong-in of Alpha Sea Rescue Co. first offered several days ago.

The diving bell provides oxygen to divers and allows them to stay underwater longer. The coast guard previously said the current and water depth at the site made the bell unusable, but on Friday the government announced that it would be deployed. On Saturday, Ko said the bell had not been used yet because the process of setting it up “didn't go smoothly.”

There also have been several reports in South Korean media of bodies going to the wrong families, with the error sometimes caught only after the remains were taken to a funeral home. On Friday, the government conceded that some recovered bodies have been misidentified and announced changes to prevent such mistakes from happening again.

Remains will be transferred to families when there is a match using DNA testing or fingerprint or dental records, the task force said in an “action plan.” The transfer will be temporary when a body is matched though identification or physical description, and authorities will wait for more authoritative evidence before making the transfer permanent.

The government also has been criticized for poorly regulating the ferry industry.

The Sewol was carrying an estimated 3,608 tons of cargo, said Moon Ki-han, a vice president at Union Transport Co., which loaded its cargo. That's also more than three times what an inspector who examined the vessel during a redesign said it could safely carry. It also far exceeds what the captain claimed in paperwork: 150 cars and 657 tons of other cargo, according to the coast guard.

Lee Kyu Yeul, professor emeritus in ship and offshore plant design at Seoul National University's Department of Naval Architecture and Ocean Engineering, said that the reported load could have set the ship tipping over with a significant turn. Tracking data show the ship turned 45 degrees before sinking, and crew members have reportedly said that they had tried to make a much less severe turn.

Yang, the prosecutor, said that the cause of the sinking could be due to excessive veering, improper stowage of cargo, modifications made to the ship and tidal influence. He said investigators will determine the cause by consulting with experts and simulations.

Prosecutors have conducted several raids to seize documents and have ordered a few dozen people not to leave the country.

The Korean Register of Shipping and the Korea Shipping Association, which regulates and oversees departures and arrivals of domestic passenger ships, both were raided, according to officials at both organizations who spoke on condition of anonymity because they were not authorized to speak about matters under investigation.

The shipping association issued a statement Friday saying that its chief director, Joo Sung-ho, intends to resign. Joo expressed his regrets over the accident and hoped that with lessons learned from the sinking, “our country will become a safe place without accidents,” the statement said.

President Barack Obama arrived Friday afternoon at the Blue House, South Korea's presidential residence, and presented President Park Geun-hye with an American flag that flew over the White House the day the ship sank. His first South Korean visit since Park took office last year was aimed at issues including North Korea, but he noted that his trip comes at a time of “great sorrow.”

“So many were young students with their entire lives ahead of them,” Obama said, invoking his two daughters, both close in age to many of the ferry victims. “I can only imagine what the parents are going through at this point, the incredible heartache.”

Obama also said he was donating a magnolia tree from the White House lawn to Danwon High School in honor of the lives lost, and as a symbol of friendship between the U.S. and South Korea. (AP)