Eleven crew members from a Chinese cargo ship are missing after it collided with a container vessel and sank just outside Hong Kong waters on Monday, authorities said.
The collision happened in the early hours of the morning near Po Toi Island which lies on the edge of Hong Kong's territory, a fire department spokesman told AFP.
"Two cargo ships collided and one of them sank," a police spokeswoman told AFP.
"Later one male was rescued and was sent to the hospital," she said, adding that rescue operations were underway to find the other crew members.
The survivor, who was rescued by a passing fishing boat, suffered minor injuries to his hands and feet, she said.
A fire department spokesman said the mainland Chinese cargo ship collided with a container vessel three miles (nearly five kilometres) south of Po Toi, just outside Hong Kong maritime territory.
"There 12 people in total, 11 are missing from the cargo ship" he told AFP.
Hong Kong authorities sent a helicopter and multiple police and fire department vessels to find the missing crew, and are coordinating rescue efforts with mainland Chinese officials.
Aerial footage of the scene shown on Hong Kong television showed an oil slick on the surface of the sea where the ship is believed to have gone down.
Hong Kong's waters are notoriously crowded. Hundreds of vessels, from wooden sampans to enormous container ships, ply the shipping routes that criss-cross the territory every day.
A collision in October 2012 between a high-speed ferry and a pleasure boat claimed 39 lives in the city's worst maritime disaster for over 40 years.
The tragedy shocked the Asian financial hub, one of the world's busiest ports, which prides itself on its good safety record.
In other major incidents, a 190-metre long cargo ship sank 80 kilometres (50 miles) southwest of Hong Kong in August 2013 when a powerful typhoon generated towering waves.
The 21-member crew of the bulk carrier Trans Summer were forced to abandon ship as the vessel tipped on its side and sank, triggering a rescue by two helicopter teams and a passing ship.