Tornado hits Texas Walmart sending shoppers fleeing

Horrifying video shows the moment a tornado ripped through the parking lot of a Texas Walmart Monday - part of an ongoing series of twisters that has devastated the American Southwest.   

'Get inside, run, run, run!' one person can be heard frantically screaming at a group of others as they attempt to make their way from the parking lot to the Round Rock Walmart entrance as the massive tornado approaches

Oh my God, a car!' the man yells as his camera briefly shows a vehicle being lifted and tossed off the road.

'Stay away from the windows!' he adds as he makes his way back into the store.

One woman tweeted a photo of her legs, which were bruised and bloodied, saying she got 'dragged across the Walmart parking lot by a tornado.'

The storm system that has seen a series of tornadoes overrun the region is expected to continue Tuesday, experts say, with 30million citizens in six states being told to take shelter in anticipation of more twisters.

Officials issued a tornado watch Monday to citizens of Texas, Oklahoma, Louisiana, Tennessee, Alabama, and Mississippi, as harsh weather including large tornadoes, damaging winds and hail is expected to continue Tuesday.

The twisters, spurred by a severe storm system heading east across the region, have seen countless trees in Texas and Oklahoma uprooted, homes damaged, and several roads and airports closed down.

Across Texas and Oklahoma, 20 tornadoes were reported, according to the National Weather Service.

The cyclones saw 54,000 customers had no power early Tuesday in Texas, largely in the Houston area, according to PowerOutage.us.

At least one person was killed and seven others hospitalized in Sherwood Shores, Texas, which sits on the border with Oklahoma, local outlet KTEN reported.

Rescuers are continuing to comb the rubble of wrecked homes and buildings to see if anyone was trapped by the destruction.

The tornado watch, which effects 8.5 million Americans across the aforementioned states, is set to end at 9am ET.

However, weather officials warn that as the storm system moves east Tuesday, about 20 million citizens in the Lower Mississippi Valley and central Gulf Coast region are at risk, as millions prepare for more harsh weather.

Conditions those in its path can expect include electrical storms, softball-sized hail and winds in excess of 75 mph - a marked 15 mph than some of the winds seen Monday.

Storms beginning Monday night have so far left dozens of neighborhoods from eastern Texas to northwestern Louisiana devastated by an onslaught of twister and high speed winds of at least 60 mph, outlets reported.

The severe weather, which has also so far affected parts of Oklahoma and Louisiana, is being spurred by a strong storm system that meteorologists said could press on for a few days.

Cities in the storm's path New Orleans and Baton Rouge in Louisiana, Jackson and Gulfport in Mississippi, Birmingham in Alabama, and Houston and Memphis.

Officials at the Storm Prediction Center warned Tuesday of the possibility that the storm will worsen Tuesday night, despite the tornado warning officially ending in the morning.

'Tornadoes occurring at night are more than twice as likely to be deadly as those during the day.'