The U.S. Navy said on Friday one of its destroyers collided with a merchant vessel southwest of Yokosuka, Japan, and a U.S. official said initial reports indicated multiple injuries aboard the destroyer.

In a statement, the Navy said the USS Fitzgerald collided with a merchant vessel 56 nautical miles southwest of Yokosuka and the extent of any injuries to U.S. personnel “is being determined.”

A U.S. official, speaking on condition of anonymity, said the destroyer had suffered damage, that there was some flooding, and that it could not operate on its own power.

Japan's public broadcaster NHK showed aerial footage of the destroyer, which had a large dent in the right side of the ship.

Images broadcast by NHK showed the U.S. ship has been struck on its starboard side next to its Aegis radar arrays behind its vertical launch tubes.

No apparent damage could be seen from the images below the waterline although damage on the deck and to part of the radar appeared significant.

NHK said that the commercial vessel is a Philippines container ship. A spokesman for the Philippines coast guard said he had heard of the accident but had no details since it was not in Philippine waters.

The U.S. Navy said it had requested the assistance of the Japanese Coast Guard

Such incidents are rare.

In May, the U.S. Navy's USS Lake Champlain collided with a South Korean fishing vessel but both ships were able to operate under their own power.

Situated at the approach to Tokyo bay, Yokosuka and the waters to its south are a busy commercial waterway plied by commercial vessels sailing to and from Japan’s two biggest container ports in Tokyo and Yokohama.

-Reuters