Oklahoma Governor Mary Fallin has declared a state of emergency in 22 counties due to wildfires.
The order allows state agencies to make emergency purchases needed to deliver necessary resources to local jurisdictions and is the first step towards seeking federal assistance.
Ms Fallin’s office said up to 465 square miles have burned in Beaver, Harper and Woodward counties in north-western Oklahoma and the Oklahoma Panhandle.
It said dangerous fire conditions are expected to continue throughout Wednesday.
Counties included in the declaration range from the Panhandle across the northern tier of the state from north-western to north-eastern Oklahoma.
The order is in effect for 30 days and can be amended to include additional counties if necessary.
Earlier, officials said one of three wildfires in the Texas Panhandle is now 100% contained.
The Texas A&M Forest Service said a fire measuring about 46 square miles near Amarillo was fully contained by late Tuesday afternoon.
Another fire that has burned more than 492 square miles in the north-east corner of the Panhandle near the Oklahoma border is 50% contained. It has destroyed two homes.
A third wildfire in Gray County and measuring nearly 145 square miles is 25% contained.
Phillip Truitt, a spokesman for the Forest Service, said his agency has confirmed three firefighters were injured battling the blazes. All have been released from hospitals.
Mr Truitt said the death toll in Texas remains at four: three deaths in Gray County and one in Hemphill County.