LIHU'E, Kaua'i — Three people were killed yesterday afternoon when a Heli USA tour helicopter with six people aboard crashed into the ocean off Ha'ena as a sudden, severe weather system moved across north Kaua'i.

Three men and three women were aboard the downed helicopter. It was not known whether the storm contributed to the crash.

A second helicopter owned by the same company made an emergency landing for an undisclosed reason at nearby Hanakapi'ai Beach about an hour after the first helicopter went down. There were no injuries in that landing.

A Coast Guard public affairs officer said the pilot of the crashed chopper issued a radio mayday call before hitting the water.

The call was heard by the Federal Aviation Administration and by Navy helicopters operating nearby. At the same time, a visitor who saw the crash called Kaua'i police.

The pilot and two passengers swam about 200 yards to the coastal reef near the mouth of Limahuli Stream. One made it to the beach, and two others were helped to shore by Kaua'i Fire Department personnel.

Two other passengers were pulled from the sea by a Navy SH-60 Seahawk helicopter that had been on maneuvers at the Pacific Missile Range Facility. They were taken to the missile range and then by ambulance to Kaua'i Veterans Memorial Hospital. The two passengers, identified only as a male and female, were pronounced dead at Kaua'i Veterans Memorial Hospital in Waimea, said night nursing supervisor Steve Cull.

The body of another passenger was pulled from the sunken wreckage by an off-duty Kaua'i firefighter and a county water-safety officer. No identities were released last night.

Rescuers said the helicopter sank, and that an oil slick at the site was adrift with debris.

The Coast Guard reported being called by the Federal Aviation Administration at 2:41 p.m. It dispatched a HH-65 helicopter from O'ahu and the cutter Kittiwake, as well as a smaller boat from Coast Guard Station Kaua'i at Nawiliwili.

Meanwhile, two Navy SH-60 Seahawks from the Kane'ohe-based Helicopter Squadron Light 37 diverted from training maneuvers at the Pacific Missile Range Facility.

Kaua'i County water-safety officers were also at the scene, and were later joined by county firefighters.

Once the six people aboard the chopper were accounted for, the Coast Guard helicopter flew two miles further to Hanakapi'ai Beach to check on the second helicopter.

A Coast Guard public affairs release said the aircraft had landed safely, and while the pilot stayed with the vehicle, a Coast Guard boat evacuated the six passengers from the remote beach.

The pilot told authorities the helicopter had encountered wind shear just off Ke'e Beach Park, according to Scott Ishikawa, a spokesman for the state Department of Transportation.

Kaua'i North Shore residents said a powerful rainstorm swept quickly through the area shortly after 2 p.m. Flash flooding from the rainstorm crossed Kuhio Highway at Manoa Stream, and at 3 p.m. was slowing ambulance crews trying to reach the helicopter passengers who had swum to shore.

National Weather Service forecaster Ray Tanabe said the system was visible on weather radar and that the weather service received reports of thunder in the area.

"There is a real unstable air mass over the state. I'm sure there were thunderstorms in the area. It popped up really quickly and then dissipated just as fast," he said.

Both aircraft were Aerospatiale AS350 helicopters, operated by Heli USA, based at Princeville Airport.

The firm also has helicopter tour operations on O'ahu, Las Vegas and the Grand Canyon. On Kaua'i, Heli USA yesterday was referring calls to a Mainland company vice president, John Power, but calls to his number were not answered. The firm's local office had no statement last night.

Yesterday's crash occurred almost exactly a year after a Bali Hai helicopter crash near Mount Kahili on Kaua'i killed five people.

The crash site is just a few miles from where a Papillon Helicopters tour aircraft went into the water off the Na Pali Coast in 1994.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.