Rescuers searched for four people missing on Wednesday after flash floods in southern Utah killed at least 16 people in a national park and a small town on the Arizona border.
In a double tragedy for the state, a wall of water and debris swept through the community of Hildale, Utah, on Monday afternoon, sweeping away two cars and killing at least a dozen people. One person is yet to be found, officials said.
At about the same time, a group of seven people set off to explore canyons in Zion National Park, about 20 miles (32 km) to the north, before the torrential downpour began.
Four bodies have been recovered there, and three people are missing, park officials said, adding the search was hampered by more bad weather and the threat of further floods.
Park officials said the group was seen entering the narrow Keyhole Canyon, a challenging route on the east side of the park which requires visitors to swim through several pools of water and rappel down steep slopes.
Authorities are withholding the identities of the dead and missing pending until relatives are notified.
In Hildale, hundreds of volunteers from more 30 agencies, supported by the National Guard, worked through the day on Tuesday to search for the missing and clear thousands of tons of mud and debris.
The floods hit two vehicles packed with 16 people on Monday. Three of the occupants escaped, but the rest were washed away. Twelve bodies were recovered on Tuesday, some of them miles downstream in Arizona.
One person, a boy, was still missing on Wednesday.
"We are committed to finding him," Washington County officials said in a statement overnight.
Hildale, home to fewer than 3,000 people, is twinned with Colorado City, across the border in Arizona.
Both cities are home to the polygamous Fundamentalist Church of Jesus Christ of Latter-day Saints. That sect is not affiliated with the Salt Lake City-based Church of Jesus Christ of Latter-day Saints, which renounced polygamy in 1890.