East Franklin Township police Sgt. W.C. Evans tells The Associated Press that police hope surveillance video and some witnesses will help police understand how the 51-year-old woman caught fire Monday.
Police have identified the woman, but the AP is not reporting her name because the cause of the fire remains unclear.
Armstrong County 911 dispatchers say the incident happened about 40 miles northeast of Pittsburgh at pumps owned by a Shop 'n Save store in the Franklin Village Mall.
A supermarket official says he's been told by police not to comment.
The woman has been flown to a Pittsburgh hospital where her condition was not immediately released.