Torrential rains, record flooding and landslides, and a melting snowpack prompted the closure of the Yellowstone National Park in the United States on Monday, said the park superintendent.
Electricity was cut off, and officials shut down all entrances for the first time since 1988, just at the beginning of the summer tourist season. It was not immediately clear how many visitors were stranded, or forced to leave the park.
"It is likely that the northern loop will be closed for a substantial amount of time," the park superintendent Cam Sholly said in a statement.
Yellowstone was preparing for its 150th anniversary year, with tourism expected to pick up after two summers of COVID-related closures.
Officials said they were assessing damages, but no injuries had so far been reported. Homes and other structures were destroyed, bridges washed away, and mudslides left small communities isolated. People had to be evacuated by boat and helicopter.
It is unclear how many residents outside the park have been rescued and evacuated.
Unprecedented rains, snow meltoff
The flooding and slides were triggered by days of unprecedented torrential showers in the park and steady rains across much of the wider Intermountain West. The area saw its wettest spring in several years.
A sudden spike in summer temperatures during the past three days also has quickened the melting and runoff of snow accumulated in the park's higher elevations from late-winter storms.
The northern part of the park and Yellowstone's gateway communities in southern Montana saw some of the most severe damage. Footage by the National Park Service showed a slide, washed out bridges and roads undercut by churning floodwaters of the Gardner and Lamar rivers.
Towns in Montana isolated
Access was cut from Gardiner, Montana, a town of about 900 people near the confluence of the Yellowstone and Gardner rivers. Cooke City was also isolated by floodwaters and evacuations were also issued for residents in Livingston.
Officials in Park County said that extensive flooding throughout the county also had made drinking water unsafe in many areas.
The Montana National Guard said Monday it sent two helicopters to southern Montana to help with the evacuations.
Scientists believe extreme weather events happening across the world are linked to climate change.
Yellowstone got 2.5 inches (6 centimeters) of rain Saturday, Sunday and into Monday. The Beartooth Mountains northeast of Yellowstone got as much as 4 inches (10 centimeters), according to the National Weather Service.
The sprawling area is known as the world's first national park, established in 1872. It is one of America's top outdoor travel destinations, famed for its geysers, abundant wildlife and scenery. It occupies some 2.2 million acres (890,308 hectares).