LAPORTE, Ind. (AP) — A northern Indiana fire official says a natural gas explosion is suspected in a house fire that killed two women.

LaPorte Fire Chief Andy Snyder says a gas line had been worked on one day before Wednesday’s house fire in the city about 20 miles west of South Bend.

But Snyder says it could not be conclusively determined whether that work was related to the deadly explosion and fire.

The (Northwest Indiana) Times reports that 72-year-old Lois K. Plotner died Wednesday afternoon at a Chicago-area hospital, while 62-year-old Tracy Swanson died Thursday at the University of Chicago Medical Center.

Police said both victims lived in the downstairs apartment.

The fire remains under investigation by local fire officials and Indiana’s state fire marshal.