OSAGE COUNTY, Oklahoma - One of the grass fires causing smoke seen in Tulsa Saturday afternoon is in Osage County.

Firefighters said so far, the fire has burned 40 acres near the 6400 block of West 52nd Street. 

Crews have been monitoring the fire since Saturday morning. They said it is 100 percent contained. 

Firefighters said if you're sensitive to smoke, avoid spending time outside.

No injuries were reported and no structures were damaged.

Assistant Fire Chief Mike Palmer said these grass fires are taking a toll on volunteer firefighters and their equipment. 

"In Osage County, we're all getting exhausted and our fleets are getting depleted and things like that so we're definitely looking forward to the rain," said Palmer.  

Firefighters said right now, they're just putting out hotspots. 

The cause of the fire is still under investigation.