A statement released by Hong Kong's government said all of the injured were being treated in local hospitals and that nine were in a serious or critical condition.

All of those confirmed dead and most of those injured are thought to have been on board a boat owned by the Hong Kong Electric company when it collided with the ferry near Lamma Island.

It wasn't clear exactly how many passengers and crew members were on the boat when the accident occurred. They had been on an outing to watch a fireworks display in Victoria Harbour.

The government statement indicated that the search operation was ongoing.

"Rescue action will continue as Fire Service Department (FSD) cannot rule out that there are still people inside the vessel or missing."

The operation began shortly after the accident, which occurred on Monday evening local time. Officials said darkness was among the conditions that had hampered rescue workers in the early hours of the operation.

"The low visibility and many obstacles on board... made it difficult for rescue," the FSD said.

There was no immediate word on what led to the collision, but six crew have been arrested.

The Hong Kong government has called for three days of mourning starting Thursday.

pfd,rg/hc (AP, AFP)