Federal Aviation Administration spokesman John Clabes said the medical crew was responding to a traffic accident about 3 miles north of Cherokee City, near the Arkansas-Oklahoma line.
The helicopter, operated by Air Evac Lifeteam of Claremore, Okla., had just lifted off with the 71-year-old patient aboard, and reached an altitude of about 400 feet, when the chopper began to spin and fell back to the ground, crashing into a pasture, according to witnesses. The patient, who was from Texas, was pronounced dead at the scene.
The pilot and a paramedic were in serious condition. The condition of a flight nurse was not immediately available.
Air Evac is a private air ambulance company serving rural areas in parts of nine states, according to the company's Web site.
The FAA and the National Transportation Safety Board will investigate.
