CENTERVILLE, Ind. (AP) _ Investigators believe a burning cigarette ignited an oxygen tank and caused a car fire that killed an Indianapolis couple on Interstate 70.
 
  Wayne County Sheriff Jeff Cappa tells the Richmond Palladium-Item that Ronnie Joe Pratt and Deborah Pratt died Sunday afternoon  near the town of Centerville, about 60 miles east of Indianapolis. Both were 62.
 
  Two other adults in the vehicle escaped. Tina Brooks was listed in critical condition Monday at a Dayton hospital. Driver Thomas Barham II was treated and released at a Richmond hospital. Their hometowns aren’t available.
 
  A witness following the victims’ car tells police the vehicle drifted left into the median and an explosion occurred inside the vehicle.
 
  One of the victims told investigators a passenger was lighting a cigarette when the fire erupted.