Authorities said the accident happened about 7:40 p.m. on New Portland Road.
They said 44-year-old Jennifer Beaulieu of Skowhegan was traveling east when her Volkswagon Beatle left the roadway, rolled over multiple times and crashed into a cornfield.
Officials said Beaulieu was not wearing a seatbelt and that she was pinned under the car when it came to rest on its passenger side.
Beaulieu was taken to Central Maine Medical Center by LifeFlight helicopter.
Officials with the Somerset County Sheriff's Office said speed and potentially intoxicants are believed to be factors in the crash.
The investigation is ongoing.