About 15 people may be missing after a flash flood in Grand Canyon National Park, the National Park Service said in a statement Sunday.The floods hit the Bright Angel Canyon and Phantom Ranch area on Saturday, the service said, adding that it was working with Arizona authorities to evacuate people and account for missing individuals.Earlier, the park service said that more than 20 people were believed missing.There were no confirmed deaths or injuries, the park service said in an email.The flash flood, which began about 2.30pm on Saturday, was caused by rainfall on the Kaibab Plateau, it said.Torrents of water wiped out footbridges over the creek and significantly altered the landscape, widening the creek bed and creating what appeared to be a new river rapid.