A small plane en route to Payson Regional Airport from a small airfield in Queen Creek crashed Sunday morning, killing all four aboard.
Federal Aviation Administration spokesman Mike Fergus said the crash occurred at 7:25 a.m., 45 miles north of Phoenix.
The plane was a Cessna 180. The FAA said the names of the deceased could not be released until their families were notified.
He said the FAA and the National Safety Transportation Board will each conduct its own investigation into the crash.
The NTSB was on its way to the crash site from Los Angeles at press time and was not available for comment.
Fergus said the FAA investigation will look at the plane to see if faulty equipment could have caused the crash.