OZARK, Ark. (AP) — Three people were killed, and one was injured when a sightseeing helicopter crashed near a music festival in the Ozark Mountains in western Arkansas, authorities said.

Franklin County Sheriff Anthony Boen said the pilot and two passengers were killed when the helicopter that had taken off from the Backwoods music festival crashed on Sunday night. Boen says another passenger was airlifted to an Oklahoma hospital and was critically injured.

Boen said pilot Chuck Dickson of Tulsa, Oklahoma, was killed in the crash along with festival workers Sarah Hill of Austin, Texas, and Marco Ornelas of Mexico. Boen did not have ages for the three killed.

An Arkansas State Police spokesman says the helicopter was found about 500 yards (460 meters) south of the festival grounds on Mulberry Mountain.

Mulberry Mountain, which had hosted the Wakarusa festival for several years, is a popular site for multiday camping and music events. The three-day Backwoods festival featured dozens of acts, including Rezz, a Canadian DJ, and the band Umphrey’s McGee.

“Today, our hearts rest with our three team members, friends, and family of ours, who passed yesterday,” organizers posted on the festival’s Facebook page. “These three individuals were incredibly hard working and loved by our festival community, and wanted to continuously improve the experience for you, as well as others who attended every year.”

The helicopter was operated by Tulsa County Helicopters, based in Oklahoma, and a spokesman said the company did not have any comment Monday. The festival’s website last month featured an interview with the company’s operator, who said it would offer six-minute helicopter rides for $40 a person.

The National Transportation Safety Board said it is investigating the crash. A spokesman for the Federal Aviation Administration did not immediately return a call seeking comment.