IRONTON, Ohio – Firefighters are trying to contain a wildfire that has spread through an estimated 70 acres in Ohio’s only national forest.

Officials said Tuesday the fire in a section of the Wayne National Forest in southern Ohio’s Lawrence County is not threatening homes or other structures.

The cause of the fire is not known.

Forest officials said the fire has been burning mostly leafy vegetation as it makes its way along the forest floor. Firefighters have been trying to establish a containment line around the fire.