Federal Aviation Administration spokesman Ian Gregor says the Cessna 310 crashed at about 3:40 p.m. Sunday near the island's airfield, Airport in the Sky.
Authorities say two of the three people aboard had critical burn injuries.
Los Angeles County sheriff's Capt. Mike Parker says a sheriff's rescue helicopter took all three to mainland hospitals. He had no further details on their condition.
Parker says the crash started a three-acre brush fire.
County firefighters were on the scene and expect to quickly contain it without calling in outside help.