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A chartered boat packed with revelers during a holiday weekend collided with a ferry and sank Monday night off Hong Kong, killing at least eight people and injuring dozens more, authorities said.

The boat was carrying about 120 people when the accident happened near Lamma Island, off the southwestern coast of Hong Kong Island, a government statement said.

The hired vessel was carrying staff members of a utility company and their family members to Hong Kong's famed Victoria Harbour to watch a fireworks display on a long holiday weekend to celebrate China's National Day and mid-autumn festival.

The government said 101 people were rescued and the Hospital Authority said 53 people, including the eight dead, were taken to four hospitals.

"There was a boat that came in close and crashed," said Yuen Sui-see, director of operations at Power Assets Holdings Ltd., which chartered the vessel for the staff outing. "After the crash, the other boat continued away, it didn't stop." He denied the vessel was overloaded, saying it had capacity for more than 200 passengers.

Television channels showed the boat half submerged with the bow pointing straight up. Helicopters circled overhead with searchlights as government vessels surrounded the boat and divers prepared to enter the water.

Local news reports said the chartered boat was hit by a larger boat operated by the Hong Kong and Kowloon Ferry company on a regularly scheduled service. Broadcaster RTHK said the captain of the bigger ship, which was slightly damaged but able to return to port, was afraid to stop in case it sank.

"All of Hong Kong's emergency forces are focused here," said Hong Kong's leader, Chief Executive Leung Chun-ying. "Wide-ranging rescue work is being carried out on in the sea, land and in the air." Leung said he didn't know what caused the collision but promised a thorough investigation.

Survivors said the boat started sinking rapidly after the collision. One woman told local television that she swallowed a lot of water as she swam back to shore. Another man said he didn't know where his children were. Neither gave their names.

Lamma is the third-biggest island in Hong Kong and near one of the coastal Chinese city's busiest shipping lanes.