The helicopter went down in about 20 feet of water around 10 a.m., said Sarasota County Fire Department Assistant Chief Paul Dezzi.

Shortly before the crash, the helicopter had been flying close to a boat that the crew was videotaping, but it wasn't clear what caused it to go down, sheriff's Lt. Chuck Lesaltato said.

``One witness said the helicopter came close the water and somehow flipped,'' Lesaltato said. ``Debris from the helicopter hit the boat.''

Two men on the helicopter were pronounced dead after arriving on shore, Lesaltato said. A third man was flown by helicopter to Bayfront Medical Center in St. Petersburg. A hospital spokeswoman declined to release his condition until his family could be notified.

The boat operator and a model onboard the vessel were unhurt. Dezzi said the model, a nurse whose name was not immediately released, jumped in and kept the men afloat as rescue boats from more than half a dozen agencies responded.

``She dove right there into the fuel and was able to get a couple of guys out,'' he said. The men were brought ashore on police boats.

Dick Hendricks, executive vice president of Powerboat magazine's parent firm, Maple Grove, Minn.-based Ehlert Publishing Group, said the company was still trying to find out who was involved in the crash. He said the magazine had several employees and freelance contractors in the area working on a weeklong series of boat tests.

The crash occurred south of Sarasota about two miles off a southwest Florida barrier island. The Federal Aviation Administration and the National Transportation Safety

Board have been called in to investigate.