ARIZONA2 hikers missing in Grand CanyonThis undated photo provided by Mark McOmie shows Jackson Standefer. Authorities searched Grand Canyon National Park on Monday, April 17, 2017, for eighth-grader Standefer and his stepgrandmother who were swept away as they tried to cross a creek during a family trip in a remote part of the park.Mark McOmie/via Associated PressThis undated photo provided by Mark McOmie shows Jackson Standefer. Authorities searched Grand Canyon National Park on Monday, April 17, 2017, for eighth-grader Standefer and his step-grandmother who were swept away as they tried to cross a creek during a family trip in a remote part of the park.Mark McOmie/via Associated PressThis Sunday, April 16, 2017, photo provided by the National Park Service shows Tapeats Creek in Grand Canyon National Park in Arizona. Authorities are searching for Jackson Standefer, 14, and Lou-Ann Merrell, 62, after the pair lost their footing Saturday and fell into the water during a family trip in a remote area of the Arizona park.National Park ServiceIn this Jan. 10, 2012, file photo, Randy Merrell shows a custom orthotic at his lab in Dry Fork Canyon, northwest of Vernal, Utah. Family members say Merrell's wife Lou-Ann Merrell and her stepgrandson Jackson Standefer were the two hikers swept away while crossing a remote creek in Grand Canyon National Park.Geoff Liesi/Associated PressThis Sunday, April 16, 2017, photo provided by the National Park Service shows Tapeats Creek in Grand Canyon National Park in Arizona. Authorities are searching for Jackson Standefer, 14, and Lou-Ann Merrell, 62, after the pair lost their footing Saturday and fell into the water during a family trip in a remote area of the Arizona park.National Park ServiceThis undated photo released by the McCallie School in Chattanooga, Tenn., on Tuesday, April 18, 2017, shows Jackson Standefer. On Saturday, April 15, 2017, Standefer, 14, and his step-grandmother, Lou-Ann Merrell, were swept down a remote creek in Grand Canyon National Park in Grand Canyon National Park.Associated Press