SANYA, Jan. 24 (Xinhua) -- Chinese rescue teams have retrieved 17 Filipino crew members from a shipwreck in the South China Sea, authorities said on Friday.

Fifteen of those rescued are in stable condition, while two were found dead. Four others remain missing by Friday evening.

At 0:46 a.m. Friday, the Sansha maritime search and rescue branch received a report from the Hainan provincial maritime search and rescue center, which said a Singapore-registered cargo ship "DEVON BAY" en route from the Philippines to south China's Guangdong Province had lost contact in waters about 55 nautical miles northwest of China's Huangyan Dao, with a total of 21 Filipino crew members on board.

According to the provincial center, the last time of contact with the ship was 9:26 p.m. Thursday, when the ship crew reported that the hull had tilted severely and water was flooding in. Contact was lost after that while the ship's emergency wireless position indicator later sent out an alarm signal.

Upon receiving the report, the Sansha maritime search and rescue branch immediately launched a multi-agency international rescue operation.

The Chinese People's Liberation Army Southern Theater Command sent military aircraft to conduct search operations over the waters where the accident occurred. Two nearby China Coast Guard (CCG) vessels also joined the rescue mission, along with teams from the Nanhai Rescue Bureau of the Ministry of Transport.

Multiple international commercial vessels, including ships registered in Liberia, Panama, and Japan, also joined the search operation.

At 4:28 a.m. on Friday, CCG vessels found and rescued four crew members from a lifeboat. Severe sea conditions, with high winds and rough waves, posed significant challenges to the rescue operation. The search and rescue effort is still going on, said the authorities.

The 15 Filipino sailors in stable condition have received medical treatment and are under proper care on board a Chinese vessel, according to the CCG.