Maui County spokesman Rod Antone said firefighters recovered four bodies and believe they found a fifth at the crash site on the eastern part of Molokai, but they were having trouble retrieving it under the wreckage.
Blue Hawaiian Helicopters owner David Chevalier confirmed that five people were dead. He said the passengers were two men and two women taking a 45-minute tour that departed from Kahului, on Maui.
He declined to release the pilot's name because his wife had not yet been notified.
"We're extremely grieved for our pilot as well as the passengers," Chevalier said. "Something like this can't be more devastating to us."
Antone told the Honolulu Star-Advertiser that the passengers were from Pennsylvania and Ontario, Canada. Maui County didn't immediately return a phone call from The Associated Press seeking confirmation.
At least two of the passengers were newlyweds, the newspaper reported.
The Maui Visitors Bureau was helping families of the victims, and the Maui Police Department's chaplain was on site, county officials said.
The EC-130 chopper that crashed was less than a year old and was being leased from Nevada Helicopter Leasing LLC, Chevalier said.
Kilohana Elementary School's health aide saw the helicopter hit the hillside in the mountains above the campus, and there was a large boom, said Principal Richard Stevens.
"We just had a heavy downpour. We made the assumption it was thunder," Stevens said. "You could see smoke coming up, even though it was very cloudy."
The helicopter was engulfed in flames, said Federal Aviation Administration spokesman Ian Gregor. From the school, its yellow tail could be seen pointing up from the ground.
The crash caused a brush fire but flames didn't spread beyond the crash site, fire officials said.
Stevens went into all of the classrooms and instructed the 71 students to stay inside.
"We didn't go on lockdown," he said. "The kids were never in any immediate danger."
The campus, about a quarter mile from the crash site, was being used as a staging area for emergency workers.
Molokai is a mostly rural island of about 7,000 people between Maui and Oahu, where world leaders have gathered this week for the Asia-Pacific Economic Cooperation summit in Honolulu. Antone told the Star-Advertiser that initial indications were none of the four passengers was in Hawaii to attend the summit.
Helicopter tour companies advertise trips to Molokai to see the island's sea cliffs and Hawaii's tallest waterfall. The remote Kalaupapa peninsula on Molokai is where Hawaii exiled leprosy patients between 1866 and 1969.
Tour helicopters have come under heavy scrutiny over their safety in recent years around the country, most recently after a deadly chopper crash in Manhattan last month. Some lawmakers called for a ban on tourist flights and pleasure trips by privately owned aircraft in Manhattan following that crash.
Blue Hawaiian conducts 160,000 tours each year on all of the Hawaiian islands, Chevalier said.
A Blue Hawaiian helicopter was previously involved in a July 2000 crash that killed seven people on Maui. Pilot Larry Kirsch, 55, and six passengers died when the twin-engine AS-355 crashed into a steep mountainside deep in Maui's Iao Valley.
A National Transportation Safety Board report on that crash said the pilot was responsible. He failed to maintain enough altitude over the terrain amid low-lying clouds, and the helicopter slammed into the side of a ridge in the valley, the report said.
There have been other tour helicopter crashes in the islands over the years.
In March 2007, four people died when a Heli-USA Airways helicopter crashed at Princeville Airport on Kauai.
Three passengers drowned in 2005 after a helicopter crashed into the ocean off the coast of Kauai. The previous year, five people were killed when a helicopter crashed into a mountain on Kauai.
Associated Press writer Audrey McAvoy contributed to this report.