YOUNGSTOWN, Ohio - One woman is dead and another is critically injured after a gruesome one vehicle accident Friday in Youngstown that had the Himrod Avenue Expressway shut down for hours.

Twenty-four-year old Johnikka Waller of Youngstown was killed. Her sister 32-year-old Tamika Robinson remains in critical condition.

Police still don't know who was driving. Traffic investigators say the victims were not wearing their seat belts and they suspect speed may have been a factor in the deadly crash.

Walker was killed on impact after being ejected from a navy blue Suburban as it was traveling east bound on the Himrod Avenue Expressway just after 10:30 a.m. Friday.  

Robinson was rushed by ambulance by to Saint Elizabeth's Trauma Unit.  She suffered injuries to her face head and arms.

As traffic investigators work to re-construct what happened, and gather the trail of evidence that litters the road, they see evidence that the vehicle likely struck the concrete barrier as it came around a curve and flipped over.

Police said they do not believe any other vehicles were involved.

One woman, who recognized the vehicle, stopped at the scene and was crying and devastated beyond words.