Tornadoes, Lightning, Hail. . .

Severe weather has swept the nation, with high winds, thunderstorms, and damaging hail.

In West Salem, Wisconsin, the big top turned into a major flop when strong winds toppled a circus tent, injuring at least 13 people.

"It was terrifying. All the poles were lifting," Analia Galarreta, a circus performer at Sterling & Reed Circus, told CBS News.

The toppled tent trapped adults and children in the audience. Circus animals were also caught in the scramble to get out of the mass of tarp, rope and poles.

One man was trampled by a horse that had been spooked in the chaos. Emergency crews quickly responded to the scene and said the situation could have been a lot worse.

In Nashua, Iowa, the Army National Guard was helping residents clear away fallen trees and salvage what's left of damaged homes after tornadoes battered the area. Two tractor-trailers were blown off the road in the storm, injuring two people. Torrential rains fell at an estimated four inches per hour.

Winds estimated at 80 miles-per-hour knocked out power, downed trees, and tore up homes, barns and businesses in and around Cedar Rapids and Waterloo.

Iowa Gov. Terry Branstad on Thursday evening added two counties to the list of disaster areas around the state.

Other parts of the Midwest are knee-deep in water. In Fargo, N.D., roads have quickly turned into lakes, stranding drivers and forcing pedestrians to wade through the streets. The storms spawned a few tornadoes in Bismark. So far, there have been no reports of serious injuries.

In Kansas City, Mo., drivers coped with a different problem - hail the size of golf balls.

Lightening also struck several homes in Hawthorne Woods, Ill., sending them up in flames.