A US Navy destroyer has collided with a merchant ship off the coast of Japan, the U.S. military said, and there have been injuries. The US 7th Fleet says on its Facebook page that the collision was with Philippine-flagged merchant vessel ACX Crystal. The fleet says it is working with the Japanese Coast Guard to conduct a medical evacuation for a sailor by helicopter, and that there are currently no reports of casualties. Live footage shot from a helicopter Saturday morning by Japanese broadcaster NHK showed heavy damage to the mid-right side of the Navy ship, which appeared to be stationary in the water. People were standing on various parts of the deck. The Navy said that the USS Fitzgerald collided with a merchant ship 56 nautical miles southwest of Yokosuka, Japan, a city south of Tokyo that is home to a U.S. Naval base. A U.S. defense official said there is flooding in three compartments of the Fitzgerald, and there were injuries. The 7th Fleet says the ship experienced flooding in some areas, and it is heading back to Yokosuka. The Pacific Fleet said the extent of injuries and damage to the Fitzgerald are being determined, and the incident is under investigation.