(CNN) -- Three people died Thursday when a medical helicopter crashed in western Tennessee, the Federal Aviation Administration said.
The helicopter had dropped off a patient in Jackson, Tennessee, and was returning to Brownsville, Tennessee, about 30 miles west of Jackson, when the crash was reported, said FAA spokesman Lynn Lunsford. Tennessee Emergency Management Agency spokesman Jeremy Heidt said the crash occurred shortly after 6 a.m.
Three people were initially reported to be on board the helicopter, Lunsford said. All three were believed to be fatalities, as the aircraft -- a Eurocopter AS350 -- was burned, he said.
Investigators were en route to the scene of the crash, a field near Brownsville, Lunsford said.
CNN affiliate WMC-TV said the helicopter was operated by Hospital Wing. The organization identifies itself on its Web site as the Memphis Medical Center's air ambulance service.
Hospital Wing said in a statement, reported by WMC-TV, that the crash occurred just east of Brownsville, and that three crew members and no patients were on board. The National Transportation Safety Board and the FAA are investigating, the statement said.
"Nothing like this has ever happened in our history," Allen Burnette, Hospital Wing's director and chief operating officer, said in the statement.
"A weather report said there were thunderstorms in the area, but that they had passed, Lunsford said. "The big weather system moving through had stopped a few moments before."
Officials believe the helicopter was operating under a visual flight rules plan and not communicating with air traffic controllers, he said. Visual Flight Rules, or VFR, mean a flight is conducted under visual conditions.
"There are operating guidelines in any aviation operation, but ultimately the pilot is responsible for (the) safety of (the) aircraft and deciding whether to go forward or not," Lunsford said.
Hospital Wing was founded in 1985, the group's statement said, and is a nonprofit air medical transport service with direct alliances with the Methodist Le Bonheur Healthcare, Baptist Memorial Hospital, The MED, St. Francis Hospital in Memphis and Crittenden Memorial Hospital in West Memphis, Arkansas.
CNN's Carolina Sanchez contributed to this report.