Communities bordering Yellowstone National Park are isolated and tourists stranded after record floodwaters knocked out roads and bridges in Montana and Wyoming and forced the closure of all entrances to the park.
The flooding followed a torrent of rain that combined with a rapidly melting snowpack, just as the summer tourist season was ramping up.
While numerous homes and other structures were destroyed, there were no immediate reports of injuries.
Yellowstone officials said they were assessing damage from the storms, which washed away bridges, caused mudslides and forced evacuations by boat and helicopter.
It is unclear how many visitors are stranded or have been forced to leave the park and how many people who live outside the park have been rescued and evacuated.
Some of the worst damage happened in the northern part of the park and Yellowstone’s gateway communities in southern Montana.
National Park Service photos of northern Yellowstone showed a mudslide, washed out bridges and roads undercut by churning floodwaters of the Gardner and Lamar rivers.
The flooding cut off road access to Gardiner, Montana, a town of about 900 people near the confluence of the Yellowstone and Gardner rivers, just outside Yellowstone’s busy North Entrance.
Cooke City was also isolated by floodwaters and evacuations were issued for residents in Livingston.
Evacuations and rescues were ongoing and officials urged people who were in a safe place to stay put overnight.
The Montana National Guard said on Monday that it had sent two helicopters to southern Montana to help with the evacuations.
Cory Mottice, a meteorologist with the National Weather Service in Billings, Montana, said rain is not in the immediate forecast, and cooler temperatures will lessen the snowmelt in coming days.
“This is flooding that we’ve just never seen in our lifetimes before,” Mr Mottice said.
The Yellowstone River at Corwin Springs crested at 13.88ft on Monday, higher than the previous record of 11.5ft in 1918, according the the National Weather Service.
The flooding also affected the rest of the park, with officials warning of higher flooding and potential problems with water supplies and wastewater systems at developed areas.
Yellowstone had 2.5in of rain on Saturday, Sunday and into Monday, and the Beartooth Mountains north east of Yellowstone had as much as 4in, according to the National Weather Service.
The flooding happened while other parts of the US burned in hot and dry weather. More than 100 million Americans were being warned to stay indoors as a heatwave settled over states stretching through parts of the Gulf Coast to the Great Lakes and east to the Carolinas.
Elsewhere in the West, crews from California to New Mexico are battling wildfires in hot, dry and windy weather.