Tornadoes and violent storms struck parts of the South and Midwest on Wednesday, killing at least one person, knocking down power lines and trees, ripping roofs off homes and shooting debris thousands of feet into the air. A tornado emergency was briefly issued in northeast Arkansas, with the National Weather Service telling residents on social media: “This is a life threatening situation. Seek shelter now.” Amateur video showed a massive funnel cloud in Lake City, which is in northeast Arkansas. Dozens of tornado and severe thunderstorm warnings were issued in parts of Arkansas, Illinois, Indiana, Missouri and Mississippi as storms hit those and other states in the evening. Forecasters attributed the violent weather to daytime heating combining with an unstable atmosphere, strong wind shear and abundant moisture streaming into the nation's midsection from the Gulf. The Missouri State Highway Patrol said at least one person was killed Wednesday in southeast Missouri, KFVS-TV reported. The coming days were also forecast to bring the risk of potentially deadly flash flooding to the South and Midwest as severe thunderstorms blowing eastward become supercharged. The potent storm system will bring “significant, life-threatening flash flooding” each day through Saturday, the National Weather Service said. With more than a foot (30 centimeters) of rain possible over the next four days, the prolonged deluge “is an event that happens once in a generation to once in a lifetime,” the weather service said. “Historic rainfall totals and impacts are possible.” More than 90 million people were at some risk of severe weather in a huge part of the nation stretching from Texas to Minnesota and Maine, according to the Oklahoma-based Storm Prediction Center.