Four people have died in the crash of a contractor's helicopter on the Hawaii island of Kauai, the US navy said on Tuesday.
The Pacific missile range facility said the aircraft crashed on the north side of the installation shortly after 10 am. There were no survivors. The names of those killed were not yet available, it said.
The helicopter was being flown by Croman Corporation in support of a training operation, the missile range facility said in a news release.
The National Transportation Safety Board said in a tweet the agency is investigating the crash of the Sikorsky S-61N helicopter.
The Sikorsky S-61N was built between 1959 and 1980 by Sikorsky Aircraft, which is now part of Lockheed Martin.
It was designed to carry a substantial freight or up to 30 passengers, according to historical archives.
The helicopters were optimized for use over water, for example, to support oil rig operations. Versions were also used by all branches of the US military.
Licensees in the United Kingdom and other countries have also built the aircraft.
A Kauai county spokesperson said county police and firefighters responded and were assisting the military.
Kauai police were helping the navy with perimeter security and investigation support, said Coco Zickos, a county spokesperson.
However, An investigation will be conducted to determine the cause of the crash, the missile range facility release said.
The Pacific missile range facility is a navy base on the western edge of Kauai where the military tests missile defense technology and various units conduct exercises.