Egyptian authorities said more than a dozen people, mostly foreigners, were still missing after a tourist yacht capsized in the Red Sea on Monday, with 28 others rescued.

The vessel carrying 31 tourists of various nationalities and a 13-member crew sent out a distress call at 5:30 am (0330 GMT), a statement from Egypt’s Red Sea governorate said.

It said 16 people are missing — 12 foreigners and four Egyptians — revising an earlier figure of 17 missing.

The statement said the boat, the “Sea Story”, is owned by an Egyptian national.

On board were people from Belgium, Britain, China, Finland, Germany, Ireland, Poland, Slovakia, Spain, Switzerland and the United States.

The yacht embarked on Sunday on a multi-day diving trip from Port Ghalib near Marsa Alam in the southeast, and had been due to dock on Friday at the town of Hurghada, 200 kilometres (124 miles) north.

Governor Amr Hanafi said some survivors were rescued by an aircraft, while others were transported to safety aboard a warship.

“Intensive search operations are underway in coordination with the navy and the armed forces,” Hanafi added in a statement.

In video footage released by the State Information Service, Hanafi was seen speaking in Marsa Alam to survivors from the incident.

Beijing’s embassy in Egypt said two of its nationals were “in good health” after being “rescued in the cruise ship sinking accident in the Red Sea”, according to Chinese state media.

The Finnish foreign ministry confirmed to AFP that one of its nationals is missing.

Polish foreign ministry spokesman Pawel Wronski said authorities “have information that two of the tourists may have had Polish citizenship”.

“That’s all we know about them. That’s all we can say for now,” he told national news agency PAP.

The Red Sea governor said initial reports suggest “a sudden and large wave” struck the boat, causing it to capsize within 5-7 minutes.

Some passengers were unable to escape as they were inside their cabins at the time, he added.

‘Hit by a wave’

According to a manager of a diving resort close to the rescue operation, one surviving crew member said they were “hit by a wave in the middle of the night, throwing the vessel on its side”.

The governor said the vessel had passed its latest safety inspection in March this year, with no technical issues reported.

Authorities in the Red Sea capital of Hurghada on Sunday shut down marine activities and the city’s port due to “bad weather conditions”.

But winds around Marsa Alam had remained favourable until Sunday night, the diving manager told AFP, before calming again by morning.

By Monday afternoon, it had become increasingly unlikely that those missing would be rescued “after 12 hours in the water”, he said, requesting anonymity because he was not authorised to speak to the media.

The Marsa Alam area saw at least two similar boat accidents earlier this year but there were no fatalities.

The Red Sea coast is a major tourist destination in Egypt, a country of 105 million that is in the grip of a serious economic crisis.

Nationally, the tourism sector employs two million people and generates more than 10 percent of GDP.

Dozens of dive boats criss-cross between Red Sea coral reefs and islands off Egypt’s eastern coast every day, where safety regulations are robust but unevenly enforced.

Earlier this month, 30 people were rescued from a sinking dive boat near the Red Sea’s Daedalus reef.

In June, two dozen French tourists were evacuated safely before their boat sank in a similar accident.

Last year, three British tourists died when a fire broke out on their yacht, engulfing it in flames.