"Getting out of the aircraft was important," he said. "It was, extremely, a team effort on many people to take care of them."
The pilot of the 2002 Cessna Grand Caravan was physically OK, said Schuman, who declined to release his name. Little information was available on the conditions of the other passengers.
Maui County officials said the National Transportation Safety Board was investigating the crash that occurred on Wednesday and killed health director Loretta Fuddy.
The plane, bound for Honolulu, went down about a half-mile northwest of Kalaupapa peninsula, Maui Fire Department spokesman Lee Mainaga said in a statement.
Schuman said he did not yet know why the engine failed because he has not been able to see the plane. It crashed soon after takeoff, after getting into the air and making its turn toward Honolulu, he said.
Schuman said the plane had no previous problems.
"There's only one engine on that plane and when it quits on you, you just have to deal with it in that moment," he said.
Federal Aviation Administration spokesman Ian Gregor said investigators planned to speak with the pilot and some passengers on Thursday.
The location of the wreckage combined with wind and wave conditions likely means it won't be recoverable, NTSB spokesman Eric Weiss added.
It was Fuddy who released President Barack Obama's birth certificate in 2011 after he and his personal attorney wrote to Fuddy to make public his original birth certificate and relieve the state from the burden that came with repeated inquiries.
Fuddy said then that she had viewed the records that "further prove the fact that he was born in Hawaii."
Fuddy, 65, and deputy director Keith Yamamoto were on the flight after an annual visit to Kalaupapa, a remote peninsula on the north side of Molokai (moh-loh-KY'-ee) island where the state exiled leprosy patients until 1969.
Tom Matsuda, interim executive director of Hawaii's health insurance exchange, confirmed the death of Fuddy, who was on the board of the exchange.
"I cannot even begin to convey what a terrible loss this is for Hawaii," Matsuda said in a statement. "I worked closely with Director Fuddy on the Affordable Care Act and came to know and respect her as a passionate advocate for public health and a warm, caring human being."
Gov. Neil Abercrombie said Fuddy was loved and respected.
"Her knowledge was vast, her counsel and advice always given from her heart as much as from her storehouse of experience," Abercrombie said.
Rev. Patrick Killilea, pastor of St. Francis Church at Kalaupapa, recalled how he made sign of the cross on Fuddy's forehead when her body was taken to a care home after the crash.
"I did give her conditional last rites, not knowing exactly what time she passed," he said. "From what I understand, she could have been deceased for a couple of hours."
The priest said Yamamoto shared how he had held Fuddy's hand in the water after the plane went down.
"They were in their life preservers," Killilea said. "At some point she let go, and there was no response."
U.S. Sen. Brian Schatz, a former lieutenant governor under Abercrombie, said Fuddy was capable and caring. His office said Fuddy spent 30 years working in health and human services and had been health director since March 2011.
Most recently, Fuddy led the department as it transitioned its marriage license system to allow gay couples to wed under a new law that took effect this month.
Coast Guard Petty Officer Melissa McKenzie said a Coast Guard helicopter rescued three passengers from the water and Maui fire crews picked up others. One person swam ashore.
McKenzie said the helicopter transported three people to Honolulu for medical treatment, while a Coast Guard plane took five people to Maui.
The leprosy settlement on Kalaupapa is still run by the state health department, though only a few former leprosy patients continue to live there.
Associated Press writers Oskar Garcia and Jennifer Sinco Kelleher contributed to this report.