The driver's name and age have been released.

Oregon State Patrol investigators are trying to find out what caused a 76-year-old driver to veer off I-84 near Meacham, OR Thursday afternoon.

The woman, Barbara May Nash of Pendleton, was Eastbound near Meacham, about 20 miles Southeast of Pendleton.    According to witnesses,   Nash was traveling in the left lane, then drifted across the freeway, onto the shoulder.   Her 2004 Chevy Blazer then sped about another 400 feet on the roadside gravel before going up a hillside, flipping and landing on top of the guardrail.

She was pronounced dead at the scene. Authorities don't know if a medical situation led to the crash,  authorities didn't say if she was wearing a seatbelt.

I-84 fatal near Pendleton (Courtesy Oregon State Patrol)