JACOB LAKE, Ariz. (AP) — Visitors and staff at two national parks in the U.S. West have been evacuated because of wildfires.

Gunnison National Park, about 260 miles (418 kilometers) southwest of Denver, closed Thursday morning after lighting sparked blazes on both the North Rim and South Rim of the Black Canyon, the park said. The wildfire has burned 2.5 square miles (6.5 square kilometers), with no containment of the perimeter.

The conditions there have been ripe for wildfire with hot temperatures, low humidity, gusty winds and dry vegetation, the park said, adding that weather will remain a concern Friday.

The Grand Canyon's North Rim in Arizona also closed Thursday because of a wildfire on adjacent Bureau of Land Management land near Jacob Lake. The Coconino County Sheriff's Office said it helped evacuate people from an area north of Jacob Lake and campers in the Kaibab National Forest nearby.

The fire began Wednesday evening after a thunderstorm moved through the area, fire officials said. It has burned about 1.5 square miles (3.9 square kilometers) with zero containment.