The burning of the water treatment plant resulted in the release of chlorine gas that prompted the evacuation of firefighters and hikers from the inner canyon, park officials said Sunday. Chlorine gas is heavier than air and can quickly settle into lower elevations such as the inner canyon, posing a health risk.

The United States Postal Service (USPS) will be raising the first-class Forever stamp price, as well as other products, on Sunday, July 13, USPS Senior Public Relations Representative Marti Johnson confirmed on Saturday, July 12. "The Postal Service’s Market Dominant and Competitive Services price increases take effect this weekend," Johnson said.