HOUSTON - Fierce storms have battered vast swathes of the US Midwest and South for four days, unleashing hundreds of tornadoes, heavy rains and historic flooding that had claimed at least 16 lives as of Saturday night.

As of 7:30 pm Central Time (GMT 1230) on Saturday, more than 250,000 homes and businesses lost power in five US states due to the severe weather, data from poweroutage.com showed.

Since Wednesday, when tornadoes and flooding began sweeping parts of Midwest and southern states, 10 people have died in Tennessee, two each in Kentucky and Missouri, while Arkansas and Indiana each reported one, according to local reports.

Among the victims were a 5-year-old in Arkansas, a 9-year-old swept away in Kentucky and a 57-year-old Missouri man caught in floodwaters.

Since Wednesday, parts of Kentucky have received more than 30 centimeters of rain, leaving hundreds of roads closed due to flooding and landslides. On Saturday, the cities of Butler and Falmouth in northern Kentucky were subject to mandatory evacuations.

According to a report from weather.com, rain in just five days of April matched the average for the whole month in central Indiana.

On Saturday evening, a tornado was confirmed in northern Mississippi, while other tornadoes were reported in Tennessee. No immediate reports of severe damage or injuries were available.

Forecasters attributed the violent weather to warm temperatures, an unstable atmosphere, strong wind shear and abundant moisture streaming from the Gulf of Mexico, according to the weather.com report.