FLAGSTAFF — A wildfire that levelled a historic lodge and visitors centre on the Grand Canyon’s North Rim grew rapidly more than a week after it began as firefighters pushed ahead Monday with efforts to slow its spread.

Park officials have closed access for the season to the North Rim, a less popular area of the park that draws only about 10% of the Grand Canyon’s millions of annual visitors.

The fire destroyed the Grand Canyon Lodge, the only lodging inside the park at the North Rim, along with cabins, employee housing and a wastewater treatment plant, park Superintendent Ed Keable said Sunday.

Firefighters at the North Rim and hikers in the inner canyon were evacuated during the weekend over concerns about the fire and potential exposure to chlorine gas after a treatment plant burned.

Rafters on the Colorado River, which snakes through the Grand Canyon, were told to bypass Phantom Ranch, an outpost of cabins and dormitories at the bottom of the canyon.

Arizona Gov. Katie Hobbs on Sunday called for a federal investigation into the National Park Service’s handling of the wildfire, which was sparked by lightning July 4.

Authorities first used a “confine and contain” strategy by clearing fuel sources, but shifted to aggressive suppression a week later as the fire rapidly grew to 20 square kilometres because of hot temperatures, low humidity and strong wind gusts, fire officials said.

“Arizonans deserve answers for how this fire was allowed to decimate the Grand Canyon National Park,” the governor said in a social media post.

No injuries have been reported, but 50 to 80 structures have been lost, the park superintendent said.

There are two wildfires burning near the North Rim — the Dragon Bravo Fire that destroyed the lodge and other buildings and the White Sage Fire, which by Sunday afternoon had charred 162 square kilometres of terrain.

Officials reported progress in battling the White Sage Fire.

The Grand Canyon Lodge, known for its huge ponderosa beams, massive limestone facade and a 600-pound (272-kilogram) bronze statue of a donkey named ʻBrighty the Burro,ʻ was perched on the edge of the North Rim and offered sweeping views of the canyon.

Aramark, the company that operated the lodge, said all employees and guests were safely evacuated.

An original lodge burned down from a kitchen fire in 1932, four years after construction was completed, according to the Grand Canyon Historical Society. The redesigned lodge using the original stonework opened in 1937.

Elsewhere, a wildfire burning in southwestern Colorado closed Black Canyon of the Gunnison National Park and forced the evacuation of homes near the park. The fire was started by lightning Thursday on the south rim of the park, a dramatic, deep gorge carved by the Gunnison River. Colorado Gov. Jared Polis issued a disaster declaration Sunday because of it and other fires burning in western Colorado.