Rainfall totals of 6 inches or more were registered across the area Sunday, the National Weather Service said.
CBS "This Morning" Meteorologist Craig Allen explains that the nation's volatile weather is caused by a strong jet stream going through warm, moist air from the south and crisp, cold air. That's a mixture for severe weather, showing up in thunderstorms, tornadoes, and even snowfall in the higher elevations.
In the suburb of Blue Springs, Mo., east of Kansas City, the body of 9-year-old John W. Parmerlee was found in runoff from a cove leading to a lake behind his home.
Two more deaths were reported in suburbs in neighboring Kansas. In Overland Park, an 83-year-old man who tried to drive through high water was swept away when he tried to get out. In Lenexa, Kenneth W. Tucker, 27, was found about a half-mile from his car, which was in a creek.
At the height of the storm, the rain and lightning were so bad that the football game between the Kansas City Chiefs and the Seattle Seahawks was delayed 45 minutes. Some wind gusts reached 70 mph. In Lee's Summit, east of the city, fish were washed into roadways.
Some streets and highways continued to be blocked by high water Monday morning, making for a difficult commute in the metropolitan area.
In Oklahoma, nine people were injured in the town of Prague, about 45 miles east of Oklahoma City, when a tornado touched down Sunday night. One person was in stable condition with back and neck injuries; the rest were treated and released.
Ben Springfield, director of emergency management in Lincoln County, which includes Prague, said there were no injuries outside the town "but we probably have half a dozen houses destroyed."
In Watonga, 70 miles northwest of Oklahoma City, a 200-yard-wide tornado caused damage and power outages, while another twister in northwestern Oklahoma damaged a barn and a house.
Paul Renfrow, spokesman for Oklahoma Gas & Electric Co., said about 35,000 customers were left without power at the peak of the storms. That number had dropped to about 10,000 by Monday morning.