WOODWARD, Okla. (AP) - Firefighters are assessing damage as they work to contain a wildfire that has burned nearly 90 square miles in northwest Oklahoma.

Woodward Fire Department Chief Steve Day said Thursday that firefighters are battling fatigue after local departments that are barely free from suppressing last month's large wildfire in Oklahoma and Kansas work day and night to control this week's fire in Woodward County.

Day says no towns or cities were threatened Thursday afternoon, although oil and agriculture infrastructure were at risk.

It's still unclear how many structures have been destroyed by the blaze.

The Woodward County fire is the largest active fire that Oklahoma Forestry Services is monitoring.