Japanese Coast Guard officials said it was not known whether there were any casualties, Kyodo news service reported.

The 4 a.m. collision apparently involved a 7,700-ton, 540-foot, Atago Aegis system-equipped destroyer and a fishing boat belonging to a fishery cooperative in Katsuura, Kyodo reported. Such fishing boats usually have two people on board, the news service said.

The coast guard had dispatched a patrol boat and aircraft to search the accident site.