A Japanese military helicopter carrying two crewmembers crashed in southwestern Japan on Monday, ripping the top floor off a house and setting it on fire, officials said.
The Defense Ministry said both crewmembers suffered heart and lung failure.
The Boeing AH-64 combat helicopter, belonging to the Ground Self-Defense Force's Metabaru training camp, crashed in Kanzaki city in Saga prefecture, defense officials said.
Public broadcaster NHK showed orange flames and black smoke rising from the charred house, which had its upper floor torn off. Witnesses reported a big boom and ripping noises from the sky before the crash.
The four residents of the damaged house were believed to have been away at the time of the accident, said Masaki Endo, a disaster official at the Saga prefectural government. No one else on the ground was believed to have been hurt, he added.
Defense Minister Itsunori Onodera said the helicopter fell nose down after losing contact with air traffic control. He said the cause of the accident is under investigation.
Prime Minister Shinzo Abe ordered the grounding of all 12 helicopters of the same type for safety checks, Kyodo News agency reported.
The crash follows a series of emergency landings and other incidents involving U.S. military aircraft on Japan's southern island of Okinawa.