The Grand Canyon flash flood response is continuing after intense flooding affected Bright Angel Canyon and the area around Phantom Ranch in Arizona. The National Park Service said more than 20 people might be missing or unaccounted for following the Aug. 29 event. The Associated Press reported one death and continuing rescue and evacuation work.

The Park Service said its teams, working with the Arizona Department of Public Safety and other partners, were trying to account for people who may have been in the affected area. That means the number of unaccounted individuals can change as officials match names, reports and evacuation records. It should not be read as a final confirmed death toll.

The flood also created infrastructure and access problems. Park officials said the response included evacuations and that the North Kaibab Trail and Phantom Ranch area were affected. AP reported that a pipeline was knocked out and that dozens of people were airlifted, details that show why the operation involves both rescue work and restoration of basic services.

Flash floods can move quickly through canyon terrain, where narrow channels and steep walls leave little room for water to spread safely. Visitors may be far from roads or communications, so officials’ instructions and trail closures are more reliable than informal accounts posted online. The Park Service remains the controlling source for access information.

The National Park Service asked the public for information that could help account for people after the flood and provided a phone number for tips. Relatives and companions should use the official channel rather than sharing personal information publicly. The agency’s notice does not provide a completed list of victims, and further identification work is expected.

The incident is also a warning for visitors who plan canyon travel during unstable weather. A clear sky at one location does not rule out dangerous rain upstream, and conditions can change before a traveler sees the water. Anyone in the park should check current advisories and respect closures, even when a route appears passable.

The verified update remains preliminary: one person has died, more than 20 people were potentially unaccounted for in the initial Park Service notice, and rescue teams are still working. Officials will provide the next reliable numbers after the search, evacuation and identification process advances.