A flash flood at Grand Canyon National Park in Arizona has left over 20 people missing, according to authorities. The incident occurred Sunday, prompting a search and rescue operation. Details remain scarce, and the number of missing is currently an estimate. Officials have not released information about the identities or locations of those unaccounted for. The Grand Canyon is prone to flash floods, especially during monsoon season, which brings sudden and intense rainfall. The National Park Service is coordinating the response and urging visitors to exercise extreme caution. Further updates are expected as the search continues and more information becomes available.