A medical condition is to blame for the death of a commercial truck driver who was initially reported killed in a rollover crash near Elk Mountain Monday afternoon.

William Couch, 73, of Oklahoma City, Okla. died at the scene of the crash five miles west of Elk Mountain on Interstate 80 westbound around 2:45 p.m. Monday. According to the Wyoming Highway Patrol, Couch's 2015 freightliner drifted off the interstate to the north, was overcorrected and went into a slide.

As the truck slid, the trailer split in half and the truck tripped and rolled. Couch, who was buckled up, died at the scene.

But Wyoming Highway Patrol Sgt. David Wagener says a serious medical issue, which he declined to specify due to privacy concerns, is to blame for Couch's death.

"It's pretty tough to determine until they can do an autopsy with the coroner's office to see if he did have some medical condition prior to the crash happening," Wagener says.

"They did determine that driver did have a medical condition before the crash occurred, and because of that -- based on how accident records and state statute for fatal crashes is based -- this one will not be considered a fatal crash for 2016," says Wagener.

"Once that medical condition did happen, that caused the truck to go out of control at that point," Wagener says.