Powerful waves triggered by Typhoon Chaba snapped the 200-meter-long "Fujing 001" in two when it was about 300 kilometers southwest of Hong Kong at around 7:30 A.M.
The disaster happened near the eye of the typhoon when it was moving at a speed of 144 kilometers per hour, and churning 10-meter-high waves.
Thirty sailors abandoned the engineering vessel when it broke up.
Hong Kong's Government Flying Service, or GFS, deployed a number of fixed-wing aircraft and helicopters to rescue the crew.
A rescue ship from the mainland also joined in the operation.
By the time the Hong Kong aircraft arrived at the scene, half of the vessel had already sunk.
Officers abseiled down the helicopter to rescue the crewmen, and as of 3:00 P.M., three had been winched to safety.
The survivors fear that the other crew members might have been swept away by the waves.
In a social media post, the GFS said adverse weather conditions brought on by Typhoon Chaba had made the rescue operation very difficult.
Controller West Wu told i-Cable News that metal fatigue could have led to the crack on the ship.
总监West Wu在接受有线电视新闻台采访时表示，金属疲劳可能是导致船体出现裂缝的原因 。
Wu added that some structures, such as wind turbines, near the accident's site, made their efforts much more dangerous.