Record flooding has claimed 13 lives in the US state of Missouri and forced residents of a swamped small town to flee their homes, the governor said Tuesday.

Aerial images of the evacuated town of West Alton showed muddy waters from the nearby Mississippi River swallowing homes and businesses after overflowing a levee.

Governor Jay Nixon activated the National Guard to help overwhelmed local officials manage the "historic flooding event."

Flooding began on Sunday after a massive storm system dumped as much as 10 inches (25 centimeters) of rain in some parts of the state.

The United States has been hit by a wave of wild weather that has claimed at least 49 lives and stranded millions trying to get home after the Christmas holiday.

A monster storm that unleashed rare December tornadoes, flash flooding and freezing rain killed 11 people in Texas, 10 people in Mississippi, six in Tennessee and five in Illinois.

Alabama reported two storm-related deaths while Arkansas and Georgia each blamed one death on the nasty weather.

Nixon warned things could get worse before they get better in Missouri: the Mississippi is forecast to crest nearly two feet higher than a previous record on Saturday.

Hundreds of roads have been closed due to flooding and Nixon pleaded with people not to drive around barricades.

A dozen people were killed after their vehicles were swept off flooded Missouri roads.