MONTANA, United States (AP) — Raging floodwaters that pulled houses into rivers and forced rescues by air and boat began to slowly recede Tuesday across the Yellowstone region, leaving tourists and others stranded after roads and bridges were knocked out by torrential rains that swelled waterways to record levels.

The flooding across parts of southern Montana and northern Wyoming forced the indefinite closure of Yellowstone National Park, just as a summer tourist season that draws millions of visitors annually was ramping up.

Just north of the park, hundreds of people remained isolated after the Yellowstone River and its tributaries washed away the only roadways in and out of the area.

Near Gardiner, Montana, campground manager Marshall Haley said some people had evacuated before the roads washed out, after being warned that the river was rising. But others stayed behind and now couldn’t leave, he said. There was no word on when the roads could be repaired and reopened.

“We’re on an island, so to speak,” said Haley. “Most of the motels were full, and the stores [are] going to run out of food pretty soon probably because no truck can get down here.”

The towns of Cooke City and Silvergate, just east of the park, were also isolated by floodwaters.

Numerous homes and other structures were destroyed but there were no immediate reports of injuries or fatalities.

Heavy rain on top of melting mountain snow pushed the Yellowstone, Stillwater and Clarks Fork rivers to record levels Monday, according to the National Weather Service.

Officials in Yellowstone and in several southern Montana counties were assessing damage from the storms that also triggered mudslides and rockslides. Montana Governor Greg Gianforte declared a statewide disaster.

In Livingston low-lying neighbourhoods were evacuated, and the city’s hospital was evacuated as a precaution after its driveway flooded.

It was unclear how many visitors to the region remained stranded or have been forced to leave Yellowstone, or how many people who live outside the park were 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.

Officials in Park County, which includes Gardiner and Cooke City, said extensive flooding throughout the county 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.

In south-central Montana, flooding on the Stillwater River left 68 people stranded at a campground. Stillwater County Emergency Services agencies and crews with the Stillwater Mine rescued people Monday from the Woodbine Campground by raft. Some roads in the area were closed because of flooding, and residents have been evacuated.

“We will be assessing the loss of homes and structures when the waters recede,” the sheriff’s office said in a statement.

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,” Mottice said.

Scientists say climate change is responsible for more intense and more frequent extreme events such as storms, droughts, floods and wildfires, although single weather events usually cannot be directly linked to climate change without extensive study.

The Yellowstone River at Corwin Springs crested at 13.88 feet (4.2 metres) Monday, higher than the previous record of 11.5 feet (3.5 meters) set in 1918, according the the National Weather Service.

At a cabin in Gardiner, Parker Manning got an up close view of the water rising and the river bank sloughing off in the raging Yellowstone River floodwaters just outside his door.

“We started seeing entire trees floating down the river, debris,” Manning, who is from Terra Haute, Indiana, told The Associated Press. “Saw one crazy, single kayaker coming down through, which was kind of insane.”

On Monday evening Manning watched as the rushing waters undercut the opposite riverbank, causing a house to fall into the Yellowstone River and float away mostly intact.

Floodwaters inundated a street in Red Lodge, a Montana town of 2,100 that’s a popular jumping-off point for a scenic, winding route into the Yellowstone high country. Twenty-five miles (40 kilometres) to the north-east, in Joliet, Kristan Apodaca wiped away tears as she stood across the street from a washed-out bridge, The Billings Gazette reported.

The log cabin that belonged to her grandmother, who died in March, flooded, as did the park where Apodaca’s husband proposed.

“I am sixth-generation. This is our home,” she said. “That bridge, I literally drove yesterday. My mom drove it at 3 am before it was washed out.”

On Monday, Yellowstone officials evacuated the northern part of the park, where roads may remain impassable for a substantial length of time, park Superintendent Cam Sholly said in a statement.

But the flooding affected the rest of the park, too, with park officials warning of yet higher flooding and potential problems with water supplies and wastewater systems at developed areas.

The rains hit just as area hotels had filled up in recent weeks with summer tourists. More than four million visitors were tallied by the park last year. The wave of tourists doesn’t abate until fall, and June is typically one of Yellowstone’s busiest months.

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 settles 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 were battling wildfires in hot, dry and windy weather.