Twenty-two-year-old Kari Reid was killed in a single-car accident on Thursday afternoon just outside the Plains city limits.

Although the crash is still under investigation, it is believed the accident was caused by some kind of medical emergency Reid experienced while driving.

Reid, who had just crossed the bridge near the Sanders County Fairgrounds and was heading north back into town, swerved, drove through a traffic sign and slid into the gully on the east side of the road, striking a tree.

Plains resident Carol Dosset was among the first on-scene and began CPR.

Shawn Emmett, Plains Chief of Police, arrived on scene along with detective Doug Dryden. Reid was unresponsive upon their arrival. The two determined that the accident was outside Plains city limits, and therefore the jurisdiction of the Montana Highway Patrol.

Shortly thereafter, Officer Smalley of the Montana Highway Patrol based in Superior responded.

Also responding were members of the Plains fire department and the Plains ambulance.