Officials say 57-year-old Patti Pederson of Ennis died in a vehicle crash near Norris Tuesday afternoon.
Montana Highway Patrol was called at 12:25 p.m. to mile marker 3 on Highway 84.
The woman's Mercedes SUV drifted into oncoming traffic and collided head-on with a 72-year-old Billings man driving a Chevrolet. He and his 71-year-old female passenger were taken to the Ennis Hospital.
All three crash victims were wearing seat belts. It is unknown if speed or alcohol were a factor.
The identities of the victims have not been released.