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

GRAND CANYON NATIONAL PARK, AZ (AP/AZFamily) ― A historic lodge on the Grand Canyon’s North Rim is among more than 70 structures lost as a result of a fast-moving wildfire that continues to burn out ...

The lightning-caused wildfire that consumed roughly 70 structures seemed unremarkable for days. High winds changed that.