Authorities in the Chinese island province of Hainan said the cargo vessel Khoi ​Nguyen 18 ran into trouble near Yongshu Reef, also known as Fiery Cross Reef, state broadcaster CCTV said.

The ship was carrying 62 crew members, and 39 people were rescued from the water.

What we know about the sinking incident

A Chinese rescue ship, the Nanhai Jiu 115, first spotted what was believed to be a distress flare from the vessel shortly before 6:30 pm on Saturday (1030 GMT).

The Khoi Nguyen 18 is a Vietnamese-registered ship measuring just under 70 meters (230 feet) in length, according to state news agency Xinhua.

It added that six Chinese vessels, a rescue helicopter and a Vietnamese vessel were involved in the search-and-rescue operations. : Fighting wildfires is getting harder — these tips could help

Territorial disputes in South China Sea

Beijing claims sovereignty over almost the entire South China Sea, despite the 2016 international ruling, initiated by the Philippines against China, that its assertion has no legal basis.

One of the most highly contested areas is the ​Spratly Islands, which China calls the Nansha Islands, where China has built runways ⁠and militarized artificial islands.

But ​Beijing's sweeping claims to the busy waterway overlap with those of other countries, including Vietnam, the Philippines, Brunei, Malaysia and Taiwan.