SALEM, S.D. (AP) — Authorities say the pilot found dead following the crash of a small plane in southeastern South Dakota told air traffic controllers of a medical issue shortly before the aircraft went down.

McCook County sheriff's officials say the pilot was the only one on board the single-engine plane that crashed about 2:30 p.m. Sunday. Controllers say they asked the pilot to put the plane down on a road or field to avoid losing consciousness while airborne. But the pilot didn't respond and crashed a short time later.

County Emergency Management Director Brad Stiefvater told the Argus Leader that the pilot was Comet Haraldson. Haraldson was an attorney at the Woods Fuller Shultz and Smith law firm.

The National Transportation Safety Board is investigating.