CHEYENNE, Wyo. (AP) — A new wildfire that started in the Teton Wilderness in western Wyoming over the weekend has grown to about 4,000 acres.

The North Buffalo Fire was first reported on Saturday and grew quickly because of hot, dry conditions. It is burning in mixed conifer and beetle-killed trees.

About 30 firefighters and one helicopter are trying to suppress the fire. The cause of the fire isn’t known.

In Yellowstone National Park, a lightning-caused fire about 5 miles southeast of Norris Junction also saw some growth over the weekend. The Cygnet Complex Fire is estimated at around 1,000 acres.

Heavy smoke from the fire could hinder travelers at times.