A U.S. Army helicopter crashed off the southern Japanese island of Okinawa on Wednesday, injuring seven people aboard the aircraft, officials said.

The others aboard the helicopter were uninjured, said Japanese coast guard spokesman Shinya Terada. The conditions of the injured were not immediately known, he said.

U.S. Army Lt. Col. Kevin Toner said in an email that the army was still gathering facts and that it would provide details later.

Terada said that after the crash, the damaged helicopter was sitting on a U.S. warship off the eastern coast of Okinawa, which is home to most of the U.S. troops in Japan. He said it was not immediately known whether the helicopter had crashed onto the vessel in a failed landing or if it had been plucked out of the sea after crashing there.

Japan's Defense Ministry had said earlier that the helicopter, a UH-60, crashed into the sea about 20 miles (30 kilometers) east of Kadena Air Base on Okinawa.

Japanese national broadcaster NHK showed video of the helicopter sitting on the warship, with its tail broken off and covered with an orange tarp.

The presence of thousands of U.S. troops on Okinawa — where more than half of about 50,000 American troops in Japan are concentrated — has been a source of friction. A plan formulated in 1996 between the Japanese and American governments would move U.S. Marine Air Station Futenma from a populated neighborhood to a less developed area, but Okinawans worried about safety, crime and noise want the base moved off the island altogether.

Wednesday's accident coincided with Japanese Chief Cabinet Secretary Yoshihide Suga's visit to the island for talks with Okinawa Gov. Takeshi Onaga, a vocal opponent of the relocation plan.

"For those who live near (U.S.) bases, it's a serious matter," he said at the outset of the talks, reminding Suga of Okinawa's burden and risk of accommodating the U.S. military bases.