The nearly century-old Grand Canyon Lodge in far northern Arizona was a refuge for ambitious hikers and adventurous tourists eager to bask in the magnificent views of one of the most remote and renowned landscapes in the world.

What fueled the explosive growth of the Dragon Bravo Fire was a mix of gusty winds, dry air and above-normal heat – weather conditions experts described as atypical for this time of year, when monsoonal moisture typically tamps down wildfire risk across Arizona.

A water treatment facility at the North Rim had been compromised by the fire, causing chlorine gas to fall towards the bottom of the canyon.