Oct 4 a mourning day
Leung also declared Oct 4 as a day of condolence. He and other principal officials will observe three minutes of silence in mourning outside the Central Government Offices at noon that day.
HKSAR government services, except immigration and emergency services, will stop so staff can also observe three minutes of silence at their workplaces. Hong Kong regional Flags on all government buildings will be flown at half mast for three days from Oct 4, he said.
Consolatory areas will be set up in all 18 districts of Hong Kong for the city's residents to grieve over the dead.
Commissioner of Hong Kong Police Andy Tsang said the six people operating the two vessels have been arrested, and he did not rule out further arrests. The six individuals detained were under investigation for "endangering people's lives at sea". Police will cooperate with the Coroner's Court and submit a report, if a hearing is conducted, he added.
According to a statement of Hong Kong Electric, "Lamma IV", which carried 124 passengers and crew, had sunk quickly after the collision. The company used the ship to ship some of its staff and their family members for an evening cruise to watch a massive fireworks display at the Victoria Harbor.
"Sea Smooth", which was damaged but did not capsize, was a regular ferry operated by the Hong Kong and Kowloon Ferry Company. It also carried a number of passengers.
Hong Kong is one of the world's busiest ports, but fatal ship crash accidents have been rare in its history.
"This is definitely an isolated incident. The marine territory of Hong Kong is safe," said CY Leung told the press conference.
Top leaders express condolence
Also on Tuesday, Chinese President Hu Jintao, Premier Wen Jiabao and Vice-President Xi Jinping expressed condolence over the deadly ship collision and urged the city government to spare no efforts to rescue the missing people and comfort the victims' families.
Hu, Wen and Xi had all made calls to learn about the relief work.
They urged the maritime rescue center and other involved departments to fully cooperate with the Hong Kong government in rescue and provide all the help needed.
The central government had asked neighboring Guangdong province to send four salvage vessels to help Hong Kong police with rescue work after the accident occurred.
Other leaders, including State Councilor Liu Yandong, had also convoyed sympathy to the injured and the families of the victims of the collision.
In addition, Macao Chief Executive Chui Sai-on also expressed his condolence to CY Leung in the day.