Floodwaters began receding and power was restored to tens of thousands of Chicago residents who were plagued by a storm that pummeled some areas of the city with more than 4 inches of rain.

The storm Thursday followed three days of withering heat across the nation's midsection that claimed at least eight lives. The heavy rain paralyzed transit, stranded drivers and flooded basements and underpasses.

"I was up to my knees in sewage," attorney Nigel Telman said. "Water I can understand, but I shouldn't have to deal with raw sewage in my basement."

Chicago's Metropolitan Water Reclamation District estimated that 1.4 billion gallons of water gushed into a tunnel drainage project. The 93 completed miles of tunnel were filled in one hour, officials said.

Delays of up to three hours were reported at both of Chicago's major airports Thursday, said Monique Bond, spokeswoman for the city Department of Aviation.

The heavy rain, wind and lightning strikes knocked out electricity to 56,000 Commonwealth Edison customers. Service had been restore to all but 1,000 by Thursday night, ComEd said.

Flooding and a power outage also led to the shutdown of Northwestern University's main campus in Evanston, a Chicago suburb. "We got hit pretty hard this morning with water in 20 to 30 buildings, some flooded and some with backed-up sewage," university spokesman Alan Cubbage said.

In southern Wisconsin, up to 8 inches of rain flooded roads. Flooding interrupted the broadcasts of five Madison radio stations, while lightning sparked a fire that damaged a daycare.