Story highlights Hong Kong police charge two ferry captains with manslaughter

Follows fatal ferry collision last year that left 39 people dead

Involved passenger ferry and vessel carrying revelers to National Day fireworks

Narrow sea lanes leading into Hong Kong's main harbor are some of the busiest in Asia

Hong Kong police on Thursday charged two ferry captains with manslaughter following a fatal ferry collision last year that left 39 people dead -- the city's worst maritime disaster in decades.

The two men, who were not named but whose ages were given as 54 and 56, were arrested last year along with five other crew members in connection with the collision off Lamma Island near Hong Kong on the night of October 1, 2012.

The collision involved a passenger ferry traveling from Hong Kong Island to Lamma Island and a vessel owned by the Hong Kong Electric Company, which was carrying company employees and their families to watch a scheduled fireworks display.

Survivors described how the collision upended one of the vessels, flinging passengers into the water. Rescuers picked up 123 survivors but at least 92 passengers were injured in the incident.

Passengers on board the ferries said how they had only moments to escape.

"First it was up to here and then here. The water rose so quickly," one woman, who declined to be named, told CNN affiliate i-Cable at the time. "We thought we were going to die for sure."

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According to the Hong Kong Fire Services Department, which led the rescue, the vessel began to sink quickly after the impact. It said low visibility and many obstacles on board made work difficult for rescuers.

The narrow sea lanes leading into Hong Kong's main deepwater harbor are some of the busiest in Asia, with giant commercial freighters, ocean liners, passenger ferries and private boats of all sizes sharing the waters.

Hong Kong is home to more than 200 outlying Islands, including Lamma. Hong Kong Island is on the south side of Victoria harbor, with Kowloon forming its northern shore. North of Kowloon lie the New Territories, which stretch all the way to mainland China.

The collision was Hong Kong's most lethal maritime accident since 1971, when 88 people died after the ferry Fat Shan capsized between Hong Kong and Macau during a typhoon.

The five crew members also arrested over the incident are due to answer bail in mid-April.