The incident commander on the Sheep Draw Fire in Harding County says it's the largest wildfire the state of South Dakota has seen since 2012.
After an afternoon flight over the area on Monday, fire officials pushed the estimated size of the fire to 10,200 acres.
The Sheep Draw Fire is burning in the West Short Pine Hills south of Camp Crook in Harding County.
Officials with the Great Plains Fire Information office say it has threatened four primary structures and 18 outbuildings, including natural gas wells, and that fire protection is in place.
Incident Commander Jim Strain with the South Dakota Wildland Fire Suppression Division said Monday that the firefighting effort includes people from federal, state and volunteer agencies, as well as Harding County ranchers.
Strain said about 120 firefighters are in camp and more are on order with equipment. Fire managers plan to ramp up personnel knowing that "critical incident fire weather" is forecast for Tuesday.
Strain says, "For right now we're hoping that tomorrow we can hold this fire. We're facing very critical fire weather conditions for March and April in South Dakota. This time of year to be in Red Flag for day–after–day and lack of precipitation has really given us a tough run here. So we're hoping our actions will hold it here tonight and we can take tomorrow as it comes."
Information officers say a fire investigator was on scene earlier in the day Monday trying to determine a cause, but Strain said the investigator couldn't get to the area where the fire actually started because it was burning too hot there.