EASTPORT – A 35-foot fishing vessel sank at its mooring Sunday.

No one was on board when the Sea King went down just inside the breakwater late Sunday morning or early afternoon, according to Lt. Stephanie Burns at the U.S. Coast Guard station in Southwest Harbor.

A crew on board a 27-foot Coast Guard vessel arrived at the scene, and another fishing vessel also was on scene to help with the salvage effort.

At this point, the cause of the accident has not been determined, Burns said.

Some diesel fuel had leaked from the fishing boat, Burns said. The Coast Guard’s Marine Safety Office in Bucksport had been notified late Sunday afternoon, but at that point, there was no indication of whether a cleanup operation would be necessary, the officer said.