CRETE, Neb. (AP) — A rural Nebraska man has died after his pickup slammed into a tree.

Sixty-six-year-old Dale Workman of Crete died Friday morning.

The Lancaster County Sheriff’s Office says Workman may have suffered a major medical problem before the collision. That’s because investigators believe speed, distracted driving, weather conditions and alcohol use were not contributing factors.

Workman was alone in his pickup and not wearing a seat belt. He was pronounced dead at the scene.