A 27-year-old helicopter instructor and his student, also 27, suffered non-life-threatening injuries Wednesday afternoon after a helicopter crashed in a lava field mauka of the Four Seasons Hualalai resort in North Kona, Hawaii County Fire Department officials said.

The instructor auto-rotated the helicopter down to a hard landing after the aircraft, a Robinson R22 Beta with a Lycoming engine, experienced engine failure at about 3:30 p.m., Kailua-Kona fire Capt. Michael Andrade said.

One of the men was seriously injured and had lower back pain, and the other man suffered minor injuries, fire officials said. They could not say which of the two was seriously injured.

Andrade said the chopper was damaged by the hard landing but remained upright.

The helicopter’s registered owner, Hawaii Pacific Aviation Inc., which does business in Kailua-Kona as Mauna Loa Helicopters, did not return calls to the Star-Advertiser.

The company’s website says it is "one of the top helicopter flight schools in the United States, with bases on three of the main Hawaiian Islands: Oahu, Kauai and the Big Island."

The website also says the company has "an impeccable safety record," and offers private sightseeing tours.

Ian Gregor, spokesman for the Federal Aviation Administration, said the National Transportation Safety Board and the FAA will investigate the accident, with the NTSB taking the lead.

The aircraft, identified by tail number N209KR, departed from Kona International Airport, he said.

The FAA Registry shows the two-seater is 20 years old, and has a valid FAA certificate.

The fire department was notified at 3:46 p.m. and a department helicopter arrived at the scene at 4:23 p.m.

Both injured men were taken by a fire helicopter to a waiting ambulance, which took them to the Kona Community Hospital.

The copter landed about two miles east of Mile Marker 86 on Queen Kaahumanu Highway (Highway 19), fire officials said.

Capt. Gifford Matsuoka of the South Kohala Fire Station said the site of the crash was "too much of an area for a ground crew to hunt them down."

A private helicopter also headed to the area, which assisted the fire chopper pilot in finding the downed aircraft, he said.

Matsuoka said the rough, brittle ‘a‘a lava made it difficult for the department’s helicopter pilot to find a flat landing spot. Fire rescue personnel had to walk about 80 yards to the crash scene.