JUNEAU, Alaska (AP) _ A massive hydraulic door crushed a crewman to death aboard a cruise ship that was touring Alaska early Wednesday morning, authorities said.

The death of Jai Ming Dai, 49, of Shanghai, China, is being investigated by the Coast Guard and the Alaska State Police. The accident occurred in an interior work area of the ship that is closed to passengers.

About 2,000 passengers and 750 crew members were aboard the Norwegian Sky as it approached Haines, just north of Juneau.

The large hydraulic, watertight doors seal off sections of the ship in the event of fire or flooding, and are designed to close slowly to prevent people from being caught in them, said Coast Guard Petty Officer Darrell Wilson.

``We want to make sure that all the alarms and safety mechanisms that are associated with that door are operating properly,'' he said.

Norwegian Cruise Line released a brief statement.

``NCL is cooperating fully with all local authorities and deeply regrets this sad occurrence,'' said Fran Sevcik, a corporate spokeswoman in Miami.