As heavy rains pummeled the region, a waterlogged earthen dam near Cashton, Wis., gave way with a roar overnight Monday, unleashing a wall of water through a narrow coulee filled with cabins, farm machinery, sheds, barns, fences, and the 100-year-old wood stove that Becky Gretebeck’s family had restored for her.

The flash flood left nothing behind.

“It was a wall of water, probably 20 feet high, that came down,” said Tucker Gretebeck, the owner of the nearby All Seasons Farm. “And just like taking your hand and wiping it through a snowbank, it took everything.”

It was some of the worst damage reported so far as a fresh round of storms freighted with heavy rain and hail barreled across southeast Minnesota and southern Wisconsin Tuesday afternoon just hours after the region woke to flooded roads, swamped houses and washed out bridges from the previous night’s downpour.

The one-two punch had the National Weather Service warning local residents to avoid flooded areas and move indoors. Meteorologist Paul Douglas tweeted that the area may be witnessing a 500-year “mega-rain” event, as estimates based on Doppler radar predicted another 5 to 12 inches of rain.

As of Tuesday morning, some 6 to 12 inches of rain had fallen across La Crosse, Monroe, and Vernon counties in western Wisconsin, with floodwaters inundating towns and overtaking roads.

The town of Ontario, Wis., pop. 554, was hit especially hard as the Kickapoo River overflowed its banks, swamping the town’s center. About 20 miles downstream, Viola, Wis., pop. 672, prepared for a record-breaking crest of the Kickapoo River expected by Wednesday morning.

The Crawford County Sheriff’s Office, meanwhile, warned residents living in Soldiers Grove, Gays Mills, and Steuben, Wis., that the Kickapoo would rise 6 to 10 feet above flood stage Wednesday and into Thursday morning.

Flooding also closed Interstate 90/94 in the Mauston area of central Wisconsin between La Crosse and Madison.

More than 100 people were evacuated overnight Monday from Coon Valley, a small town southeast of La Crosse where 38 roads in Vernon County were closed.

Across the border in Minnesota, the National Weather Service reported a pair of weak tornadoes Monday about an hour south of the Twin Cities in the towns of Nerstrand and Vasa. The twisters were classified as EF0 tornadoes, which have wind speeds between 65 mph and 85 mph.

Significant damage to a hangar was reported at the Red Wing Airport, where wind gusts reached 82 mph Monday evening, the National Weather Service said.

The severe weather forced the Red Wing City Council to delay its Monday meeting as those attending took cover in the basement.

More than 5 inches of rain fell across Houston County in southeastern Minnesota where flash flooding was reported.

On Tuesday, massive flooding across western Wisconsin made roads impassable, prompting a National Weather Service warning.

“Life threatening flooding is occurring now over portions of southeast Minnesota into southwest and central Wisconsin. Many roads under water and evacuations continue in areas,” the warning read.

Damage reports were still coming in Tuesday evening as officials assessed the situation.

Gretebeck, the farmer who was hit with flash flooding, said he heard from neighbors that houses had been torn from their foundations. The flood threw another neighbor’s truck down a valley, he said.

After the dam broke west of Cashton, the first thing it hit was Gretebeck’s pumpkin patch business, a side hustle to help his family through the ups and downs of the dairy business. He lost tractors, wagons, three cabins decorated with original murals, and the wood stove.

“Who knows how far some of that stuff went,” said Gretebeck, who said he was grateful, at least, that his house and barns were safe on higher ground.