VIBORG, S.D. — Two people died Friday when a small airplane crashed in a cornfield in southeast South Dakota.

The aircraft caught fire after it went down around 10 a.m., about 10 miles west of Viborg, Turner County Sheriff Byron Nogelmeier said. The victims, who were the plane’s only occupants, have not been identified.

“People on the ground heard a plane that was kind of sputtering, and then they heard what they called a thud,” Nogelmeier said. Details of the incident, including the cause of the crash and the airplane’s point of departure and destination, were not immediately clear. Nogelmeier said the aircraft was not a crop duster.

The National Transportation Safety Board will be responding to the scene of the accident, said spokesman Keith Holloway. The board is responsible for investigating and determining the probable cause of every civil aviation accident in the country.

Nogelmeier said a payloader is clearing a path through the cornfield to allow crews easier access to the wreckage.

“We feel bad for the individuals on the plane and the families when they find out what happened,” Nogelmeier said. “Our prayers go to them.”

This was the second plane crash in southeast South Dakota this week. On Tuesday, two people aboard a small airplane escaped injury when it crash-landed near the Sioux Falls airport.