Honolulu, Feb 23 (IANS): Four people were killed after a military-contracted helicopter crashed on Hawaii's island of Kauai, US media reported citing officials.

The crash happened at about 10 a.m. on Tuesday near Kauai's Pacific Missile Range Facility during a training operation, Hawaii News Now, a major local news outlet, reported, adding that the identities of those killed and whether they were civilians or in the military was not released.

Images posted on social media showed black smoke billowing from the crash site near the coastline, reports Xinhua news agency.

The US National Transportation Safety Board confirmed in a tweet that it's investigating the "crash of a Sikorsky S-61N helicopter near Kekaha, Hawaii".

The crashed helicopter was operated by Croman Corporation, an Oregon-based contractor, which provides "range support" to the missile facility, Hawaii News Now reported.

On the company's website, Croman Corporation claimed to be "one of the most experienced operators of Sikorsky S-61 helicopters in the world", operating a mix of twelve standard and restricted category S-61 series helicopters and three Bell 206B Jet Rangers.

The versatile platform of the S-61 can easily be configured to meet a wide variety of applications, the company said in an introduction of the helicopter.