Seven US Navy sailors are missing after their destroyer collided with a container ship near Japan, according to the Japanese Coast Guard.
At least three compartments of the USS Fitzgerald are reported to have flooded after the collision with the Philippine vessel ACX Crystal 56 miles southwest of Yokosuka.
Coast Guard official Takeshi Aikawa told Kyodo news agency that one Navy sailor had been evacuated by helicopter with a head injury but details of his or her condition are unknown.
Mr Aikawa said the US ship was not capable of moving by itself but that no damage or injuries had been reported with regards to the 29,060-tonne container ship and its crew.
The US 7th Fleet confirmed on Twitter that it was “working with the Japanese Coast Guard to conduct a medevac”, adding that any other injuries among the crew were being assessed.
The Navy would only say it was still working to account for all personnel and could not confirm anyone was missing.
In a statement, the Navy said the USS Fitzgerald had “suffered damage on her starboard side above and below the waterline” in the accident on Friday evening UK time.
It added that the ship was operating under its own power, “although her propulsion is limited”.
USS Dewey, medical assistance and two tugboats have been sent to help.
Footage on Japanese broadcaster NHK showed extensive damage to the mid-right side of the naval ship, which is an Arleigh Burke-class (Flight I) guided missile destroyer built in 1993.