Park rangers were searching Saturday for a 19-year-old woman who disappeared during a camping trip in the Grand Canyon a week ago.

Iryna Shylo, a Ukrainian citizen and Grand Canyon resident, had hiked down the canyon July 16 with a man and planned to spend the night before hiking back out the next day, said Maureen Oltrogge, a spokeswoman for the National Park Service.

The man reported Shylo missing the next morning. He said she had left the campsite to go to the bathroom and never returned. Rangers began searching for Shylo the same day.

On Friday, they found a shoe matching a description of Shylo's nine miles downstream from where she was last seen. A second shoe was found a mile farther downriver.

Thunderstorms and flash flooding along the Colorado River hindered the search Saturday, Oltrogge said. More thunderstorms were expected Sunday.