A U.S. military helicopter crashed on Monday inside an American base on the southern Japanese island of Okinawa, Japanese officials said, injuring at least one of the crew and sending up a smoke cloud that could be seen for miles. A U.S. Air Force statement said an HH-60 helicopter in the middle of a "local training mission" crashed inside Camp Hansen, in the center of the island. Japan's defense minister, Itsunori Onodera, speaking to reporters in Tokyo, said three crew members were confirmed safe and one was taken to the hospital. Onodera called the incident "regrettable" and asked for an investigation to prevent a recurrence, AP reported.