Officials found the wreckage of the two-seat plane Sunday night in the Loxahatchee National Wildlife Refuge, the South Florida Sun Sentinel reported.
The plane went down earlier Sunday, prompting a helicopter and airboat search for the wreckage, Palm Beach County Sheriff's Office spokesman Eric Davis said.
Davis said the sheriff's office is unsure of the plane's destination, from where it came or the identities of the deceased.
A pilot witnessed the crashed, which happened about 12 miles southwest of the Palm Beach International Airport, and called an Federal Aviation Administration tower in West Palm Beach, Davis said.
A spokeswoman at the FAA identified the plane as a Cirrus SR-22.
An investigation into the crash began Monday, starting with the removal of the plane and the bodies.