PAWNEE, Okla. (AP) - The Pawnee County Sheriff says his department, the state Department of Agriculture and the State Fire Marshal's office are investigating what caused a massive wildfire that killed two people, destroyed nearly 40 homes and consumed about 15,000 acres.

Sheriff Mike Waters said Thursday officials haven't determined if lightning or something else sparked the blaze, which began Aug. 7 near Oklahoma Highway 48. Waters says investigators aren't presently leaning toward arson as a cause.

The fire is being blamed for the deaths of 81-year-old Hollis Edgar of Terlton and another person, whose name Waters says hasn't been released.

Relatives said Edgar ignored warnings to evacuate. Waters says he was found behind his home Aug. 11.

The Oklahoma Insurance Department says damage estimates could reach $20 million.

Many residents weren't insured.