Snow, freezing rain and rain are underway in the southern Plains as a potent winter storm strengthens Thursday.

A powerful winter storm that dumped heavy snow and glazed roads with ice across much of Texas and Oklahoma lumbered eastward into southern U.S. states overnight, prompting governors to declare states of emergency and shuttering schools across the region.

Another blast of winter storms is closing schools, snarling flights and putting millions of residents on alert across parts of the Deep South and south-central U.S. The storm started dumping a mix of sleet and heavy snow Thursday morning in north Texas and Oklahoma,