It's possible that 20 people are still missing in Grand Canyon Flash Flooding

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While no injuries have been reported among the people rescued so far, the National Park Service stated that more than 20 people may still be missing or unaccounted for in the Bright Angel Canyon and Phantom Ranch areas. Rescuers successfully airlifted over 60 people to safety from the trails, but major infrastructure damage and trail closures remain in effect. 

 

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I believe we are still in Monsoon season throughout the deserts of the Southwestern United States that happen usually ever summer about now.