HONOLULU (AP) — A skydiving plane crashed and burst into flames just outside a small seaside airport on the island of Oahu, killing six employees of the company that operated the flight and three of its customers, officials said.

Preliminary information gathered by the Federal Aviation Administration indicated that the Friday evening crash of the twin-engine Beechcraft King Air plane happened as it took off from Dillingham Airfield on the north shore of the island, FAA spokesman Greg Martin said in a statement Saturday.

Some witnesses reported that the plane crashed as it was inbound to the airport, said Honolulu Fire Chief Manuel Neves, cautioning that those reports had not been confirmed.

The plane was operated by the Oahu Parachute Center skydiving company and the ratio of employees to customers suggested that tandem jumps may have been planned in which the customers would have jumped while attached to experienced skydivers, Tim Sakahara, a spokesman for the Hawaii Department of Transportation, told reporters.

Neves described the site of the crash near the airport’s perimeter as being “quite a ways away from the runway” and said that some family members of those aboard were at the airport when the plane went down at about 6:30 p.m.

“In my 40 years as a firefighter here in Hawaii, this is the most tragic aircraft incident that we’ve had,” Neves said.

The plane was engulfed in flames when firefighters made it to the crash site about an hour drive from Honolulu, Neves said. The victims were not identified.

Two FAA inspectors went to the crash site Friday and investigators with the National Transportation Safety Board that will investigate the crash were expected to arrive Saturday evening, said safety board spokesman Eric Weiss.

The plane with two turboprop engines was manufactured in 1967, FAA records said.

The phone for Oahu Parachute Center went unanswered Saturday.

On its web site, the company says the jumps that it offers on Hawaii are “a magical experience. There really is no better place in the world to skydive.” Its tandem jumps are listed for prices ranging from $170 to $250.

Videos from the company’s Facebook page show jumps from the same Beechcraft King Air that crashed, with customers strapped to employees and dropping from a side door of the aircraft from 10,000 feet (3,000 meters) or higher, with the Pacific Ocean and the Oahu’s green mountains far below.