BRUSSELS (AP) — Belgian regional authorities say an intact German World War I submarine has been found off the coast of Belgium and contains the bodies of 23 people.

Western Flanders Governor Carl Decaluwe told The Associated Press Tuesday that the find on the floor of the North Sea "is very unique."

He said the "impact damage was at the front but the submarine remains closed, and there are 23 people still onboard."

Decaluwe said the U-boat was found by researchers. He declined to provide details about its location until the site has been protected.

He also said he had contacted the German ambassador because "there are people on board and we need to see what can do" with their remains.