Wildfires force evacuations at two national parks in the western US

The wildfire on the South Rim has burned 2.5 square miles, with no containment of the perimeter and weather conditions worsening the fire.

Visitors and staff at two national parks in the US West have been evacuated because of wildfires. Black Canyon of the Gunnison National Park, about 260 miles (418 kilometers) southwest of Denver, closed Thursday morning after lighting sparked blazes on both rims, the park said.

South Rim of Grand Canyon National Park in northern Arizona shows smoke over the park's North Rim on Thursday (AP)

The wildfire on the South Rim 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.