MANNFORD, OK -- The Oklahoma State Fire Marshal's office is investigating Friday's grassfires near Mannford as arson.
They got the case from local departments on Monday and say there is evidence of five separate fires and ignition points.
The office doesn't have much information yet, but say they are possibly looking for a white truck.
A volunteer firefighter from Silver City died after fighting the wildfires.
Fire Chief Brutus Beall said 45-year-old John Adams died as he was backing up a fire truck. He is believed to have died from natural causes.