SAN DIEGO, Jan 27: A Navy helicopter doing training operations from a ship crashed 80 kilometres off the California coast, killing one crew member and leaving three missing long after darkness fell over the Pacific.

One sailor died on Friday after being pulled alive from the water, the Navy said.

A search-and-rescue operation was under way to locate the others, said Navy spokesman Cmdr Jack Hanzlik.

The helicopter based at Naval Air Station North Island in Coronado, California, was on a training mission when it crashed, Hanzlik said.

The MH-60S, commonly known as a Seahawk, was on a mission off the USS Bonhomme Richard, near San Clemente Island, California, directly west of the Camp Pendleton Marine base.—AP