More than two dozen crew members are missing from a ship which snapped in half after being hit by a tropical storm.
Workers were forced to abandon the industrial vessel which sank after Typhoon Chaba unleashed perilous conditions in the South China Sea, hampering rescue efforts.
Dramatic aerial footage showed people being hoisted into a helicopter by emergency crews, with at least three of the 30-strong crew brought to safety around 5.30pm local time on Saturday (around 10.30am GMT).
The disaster happened around 300km (186 miles) south of Hong Kong.
Typhoon Chaba, the first of the year to hit China, is set to bring record rainfall and a high disaster risk to provinces including Guangdong, located around 137km (85 miles) from Hong Kong.
The Hong Kong Flying Service, which dispatched six aircraft, said crew members were battling difficulties from the storm.
Chaba, the Thai name for the hibiscus flower, made landfall in the western part of Guangdong on Saturday afternoon local time, the National Meteorological Centre said.
Although the strength of the storm has now been downgraded, "extremely heavy" deluges are set to bring up to 24 inches (600mm) of rainfall in some areas.
"The abundant monsoon water vapour will lead to intense downpours and huge cumulative rainfall of an extreme nature," said the NMC's chief forecaster, Gao Shuanzhu.
Hong Kong authorities raised the typhoon warning on Thursday, just as Chinese President Xi Jinping arrived in the city to commemorate the 25th anniversary of its handover from Britain to China.
The Palace Museum, due to open on Saturday as part of celebrations to mark the 25th anniversary of Hong Kong's handover to Chinese rule, remained closed.
The treacherous conditions also forced businesses to close and triggered problems on public transport networks.
Extreme weather including unusually heavy flooding has been forecast in China through August, with climate change said to be partly responsible.