The first distress call from a sinking South Korean ferry was made by a boy with a shaking voice, three minutes after the vessel made its fateful last turn.

He called the emergency 119 number which put him through to the fire service, which in turn forwarded him to the coastguard two minutes later. That was followed by about 20 other calls from children on board the ship to the emergency number, a fire service officer told Reuters.

The ferry, MV Sewol, sank last Wednesday on a routine trip south from the port of Incheon to the traditional honeymoon island of Jeju.

Of the 476 passengers and crew on board, 339 were children and teachers on a high school outing. Only 174 people have been rescued and the remainder are all presumed to have drowned.

The boy who made the first call, with the family name of Choi, is among the missing. His voice was shaking and sounded urgent, a fire officer told MBC TV. It took a while to identify the ship as the Sewol.

“Save us! We’re on a ship and I think it’s sinking,” Yonhap news agency quoted him as saying.

The fire service official asked him to switch the phone to the captain, and the boy replied: “Do you mean teacher?” The pronunciation of the words for “captain” and “teacher” is similar in Korean.

The captain of the ship, Lee Joon-seok, 69, and other crew members have been arrested on negligence charges. Lee was also charged with undertaking an “excessive change of course without slowing down”.

Authorities are also investigating the Yoo family, which controls the company that owns the ferry, Chonghaejin Marine Co Ltd, for possible financial wrongdoing amid growing public scrutiny.

An official at the Financial Supervisory Service (FSS) told Reuters it was investigating whether Chonghaejin or the Yoo family engaged in any illegal foreign exchange transactions. The official did not elaborate.

Another person familiar with the matter told Reuters that prosecutors were looking into suspected tax evasion by the firm, its affiliates or the Yoo family with assistance from the National Tax Service. A spokesman at the tax agency declined to comment on the matter.

“There are lots of reports in the media, so as the regulator we need to check if they are true,” another FSS official said.

Several crew members, including the captain, left the ferry as it was sinking, witnesses have said, after passengers were told to stay in their cabins. President Park Geun-hye said on Monday that instruction was tantamount to an “act of murder”.

Many of the children did not question their elders, as is customary in hierarchical Korean society. They paid for their obedience with their lives.

Four crew members appeared in court yesterday and were briefly questioned by reporters before being taken back into custody. One unidentified second mate said they had tried to reach the lifeboats, but were unable to because of the tilt.

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