The Wyoming Highway Patrol is investigating a crash that killed a Gillette man Thursday afternoon.

Sgt. Stephen Townsend says the accident happened shortly before 2 p.m. roughly 20 miles east of Buffalo on Interstate 90 in Johnson County.

“The driver was westbound when, for reasons unknown at this time, his vehicle drifted off the left shoulder (and went) into the median of the interstate,” Townsend said. “It then struck a guardrail, which caused it to cartwheel one-and-a-half times.”

The driver, 77-year-old Raymond Schwindt, was found dead at the scene. Troopers say Schwindt was riding alone in his 2007 Jeep Wrangler.

Townsend says, at this time, investigators do not know what may have caused the crash.