Moscow ? An accident aboard a nuclear-powered Russian navy submarine doing a test run in the Pacific Ocean on Saturday killed more than 20 people, the navy said.

The nuclear reactor aboard the submarine was operating normally and radiation levels were normal, navy spokesman Capt. Igor Dygalo said today.

The accident occurred when a fire-extinguishing system went into operation in error aboard the submarine, Dygalo said. He said there were 208 people aboard, including 81 servicemen. The dead included sailors and shipbuilders.

The submarine was heading back to shore on its own power, and 21 people injured in the accident were evacuated to a ship that was escorting the sub.

Dygalo said the destroyer Admiral Tributs and a rescue vessel were accompanying the submarine.