The Kansas Forest Service says a wildfire that crossed into the state from Oklahoma earlier this week is considered the largest in Kansas history and one of the largest ever in the U.S.

The wildfire has burned at least 620 square miles in Oklahoma and Kansas.

The service said officials are looking at the damage in Barber County, Kansas, to determine if it meets the threshold for a FEMA disaster declaration, which would provide public assistance for damaged public infrastructure.

In Oklahoma, officials said in a release Friday there’s been very little growth in the wildfire near the town of Alva, thanks in part to “exceptional firefighting” combined with lighter winds and lower temperatures.