PUNALU`U, Hawaii - UPDATE 4/19 7:18 P.M.

The helicopter that crashed in Sacred Falls on Tuesday has been recovered.

Paradise Helicopters officials, the company who owns the aircraft told KITV4 Friday that the helicopter is now in a secured hangar. 

The Federal Aviation Administration and National Transportation Safety Board are investigating what caused the chopper to go down.

None of the four people on board were injured.

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UPDATE 5:00 P.M.

According to Paradise Helicopters, the helicopter involved in the emergency landing Tuesday was operated by K&S Helicopters dba Paradise Helicopters. 

The helicopter made the emergency landing at 11:30 a.m. Tuesday while it was operating in Sacred Falls area of O'ahu.

The helicopter was carrying three working crew members in addition to the pilot. All four onboard walked away from the aircraft after it came to a rest in trees at the bottom of a valley on the North side of Sacred Falls Valley. The passengers and pilot exited the helicopter on their own and did not require any medical attention, according to Paradise Helicopters.

The company’s Emergency Response Plan has been activated and its full resources have been mobilized to respond. K&S Helicopters is cooperating with authorities involved.

The Department of Land and Natural Resources has also released new images of the downed helicopter that are pictured here: 

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UPDATE 2:50 P.M.

The first images of rescue helicopters that responded to the downed chopper on Oahu's North Shore. 

COURTESY: Manop Karnjanaburung

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Honolulu Firefighters are responding to reports of a downed chopper on Oahu's north shore.

A chopper under contract to the DLNR Division of Forestry and Wildlife (DOFAW) made a hard landing in a remote area of the Kaluanui Natural Area Reserve above Sacred Falls on O'ahu.

According to the Federal Aviation Administration, the helicopter reportedly experienced a loss of engine power.

The helicopter was transporting one DOFAW employee and two Pacific Rim Conservation representatives. Pacific Rim is a non-profit organization that conducts field work for DOFAW.

There were two men in their 40s, and two women in their 30s on board. All were evaluated by Honolulu Emergency Medical Services, but refused transportation to the hospital. They are being transported back to Honolulu by a DLNR Division of Conservation and Resources Enforcement (DOCARE) officer.

The pilot and three passengers were not injured, and all three are hiking out of the area, DLNR reports.

The three passengers were deploying seabird song meters for population studies.

“We follow a stringent set of safety protocols and one of these protocols is known as “flight-following,” which resulted in the incident being reported very quickly. We are thankful everyone walked away from this without injury,” said Marigold Zoll, DOFAW O'ahu Branch Manager.

Both the Honolulu Fire Department and officers from the DLNR Division of Conservation and Resources Enforcement are responding.

This is a developing story, more details to come as they surface.