The medical transport plane went down in a parking lot near a casino in Elko. Local authorities said three crew members and a patient were killed. No one on the ground was hurt.
FAA spokesman Allen Kenitzer said the plane crashed under unknown circumstances.
An Elko cardiologist told the Elko Daily Free Press that the plane was transporting a heart patient to the University of Utah.
The newspaper says the plane crashed into the Barrick Gold Corp. parking lot, causing multiple explosions and sending up flames near a busy casino.
The FAA and the NTSB are investigating.
The Associated Press contributed to this report.