LAKE DELTON, Wis. — An embankment along a man-made lake gave way under severe flooding Monday, unleashing a powerful current that ripped several homes off their foundations and down the Wisconsin River.

Floodwater threatened dams across the Midwest, and military crews joined desperate sandbagging operations to hold back Indiana streams surging toward record levels. Stormy weekend weather was blamed for 10 deaths, most in the Midwest.

While the Midwest struggled with flooding, the East was locked in a sauna. Heat advisories were posted Monday from the Carolinas to Connecticut, with temperatures topping 100 from Georgia to Virginia. New York City recorded a high of 99.

In Wisconsin, an embankment forming the side of the man-made Lake Delton failed, and the water poured out into the nearby Wisconsin River. The 245-acre lake nearly emptied, washing out part of a highway, sweeping away three homes and tearing apart two others.

"It's horrible. There's no way we could stop it," said Thomas Diehl, a Lake Delton village trustee. "The breach is between 300 and 400 feet wide. The volume (of water) was just so great there wasn't anything anyone could do."

A new storm system was headed toward the Ohio Valley from the southern Plains on Monday — Oklahoma got up to 6 inches of rain by late morning and utilities reported nearly 5,000 customers blacked out — and the National Weather Service said as much as 3 inches of rain could fall on already waterlogged Indiana late Monday.

The weather service posted a tornado warning for south-central Illinois and a severe thunderstorm warning for Indiana.

By Monday morning, flooding at eight sites in central and southern Indiana had eclipsed levels set in the deluge of March 1913, which had been considered Indiana's greatest flood in modern times, said Scott Morlock, a hydrologist with the U.S. Geological Survey in Indiana.

President Bush late Sunday declared a major disaster in 29 Indiana counties. Iowa Gov. Chet Culver said nearly a third of his state's 99 counties need federal help. Wisconsin Gov. Jim Doyle had declared 30 counties in a state of emergency.

Along the East Coast, people sweltered through the heat wave.

In the fifth inning of the Kansas City Royals-Yankees game in New York, fans cheered loudly when a cloud moved in front of the sun, then booed moments later when the sun returned.

"We came to New York and the whole week is hotter than in Florida," Patti Yost, 47, of Spring Hill said at Yankee Stadium.