A Japan Coast Guard ship navigates the damaged USS Fitzgerald near the US Naval base in Yokosuka, southwest of Tokyo. Photo / AP
Seven sailors have been killed after a US destroyer has returned to port after a collision with a Philippine-flagged cargo ship off the coast of Japan, badly damaging the vessel Aided by tug boats, the USS Fitzgerald arrived back on Saturday at Yokosuka, Japan, where the Seventh Fleet is based, a statement from the navy said. The fleet's commander, Vice Admiral Joseph P Aucoin, was on the pier together with many family members when the ship arrived, it said.
"This has been a difficult day," Aucoin said, adding that the search for missing shipmates would continue now that the vessel was back in Yokosuka. "Thoughts and prayers with the sailors of USS Fitzgerald and their families. Thank you to our Japanese allies for their assistance," US President Donald Trump tweeted.
Several personnel were also injured in the incident which happened early on Saturday morning.
Among them was the USS Fitzgerald's commanding officer, Bryce Benson, who was evacuated by helicopter and was in a stable condition at a US navy hospital in the Japanese city, the navy said.
Two other sailors were also evacuated from the ship and treated for lacerations and bruises.
The collision had resulted in some flooding and damage to the ship's starboard side.
The ACX Crystal, which was carrying a crew of 20, including the captain, was "slightly damaged" in the crash, the department said.
"The ship is being ported back to Tokyo Bay and all crew have been instructed to remain on-board pending their interview by Japanese authorities later today," it added in a statement.
There was no immediate explanation as to the cause of the collision. An earlier statement from the Seventh Fleet said that the crash caused "significant damage and associated flooding to two berthing spaces, a machinery space, and the radio room".
Despite efforts to ease the intake of water, the statement said it was "uncertain how long it will take to gain access to the spaces once the ship is pier side in Yokosuka".
The names of sailors were being withheld until families had been notified.
The Japanese Coastguard assisted in the search. The USS Dewey and two navy tugs had also been dispatched to provide help, as well as helicopters and other aircraft.
Footage from the Japanese TV network NHK showed heavy damage to the mid-right side of the USS Fitzgerald and a person in a stretcher being lifted to a helicopter.
The ship's Commander Bryce Benson was taken to the US Naval Hospital in Yokosuka and was in stable condition, the US 7th Fleet said in a statement.
"Two sailors, in addition to the commanding officer, have been medically evacuated from USS Fitzgerald to US Naval Hospital Yokosuka for lacerations and bruises," it added.
The Fitzgerald began limping back to port at a slow speed, with limited propulsion after suffering damage on the starboard side below the water line that caused flooding in three compartments.
It wasn't clear yet what caused the night time collision between the destroyer and the container ship four times its size.
Most of the more than 200 sailors would have been asleep in their berthings, some of which were reportedly flooded.
The Navy said that the collision occurred 56 nautical miles (103 kilometres) southwest of Yokosuka, which is home to the 7th Fleet.
Footage showed the damaged ship moving slowly in calm seas, flanked by a tugboat.
"Right now we are focused on two things: the safety of the ship and the well- being of the sailors," Admiral Scott Swift, commander of the US Pacific Fleet, said.
The Japanese coast guard said it received an emergency call from a Philippine-registered container ship ACX Crystal in the early hours of Saturday morning that it had collided with the Fitzgerald.
Relatives of crew members were awaiting news of their loved ones.
"Of course we're nervous and scared and just praying," Rita Schrimsher said by telephone from Athens, Alabama.