A deadly storm that battered the southern United States over the weekend has moved on to the mid-Atlantic, threatening millions of people with powerful winds and possible tornadoes.

The storm left eight people dead across Louisiana, Mississippi, Alabama and Texas over the weekend, including two children who were killed after a tree fell on the car they were in. A series of severe tornadoes destroyed over 60 homes and businesses in Texas. The storm also caused havoc at Chicago’s O’Hare International Airport on Sunday, with over 1,000 flights delayed or canceled.

Describing the storm as “violent,” Mississippi Gov. Phil Bryant declared of state of emergency Sunday. He also added that conditions could have been more deadly.

“At midnight last night, I would’ve thought we would’ve had much more information to give you of a disastrous nature. Even though we have a loss of life because of the storm, it could’ve been much worse,” he said, NBC News reported.

The storm is now moving across the mid-Atlantic and Carolinas.

"The severe thunderstorms will continue to march across the Carolinas, mid-Atlantic, southern New York and into southern New England on Sunday night. The greatest threats through Sunday night will be damaging winds, flash flooding and lightning strikes, but residents should also remain alert for hail and isolated tornadoes,” AccuWeather senior meteorologist Kristina Pydynowski said.

The National Weather Service issued a severe thunderstorm warning for parts of Washington, Maryland, Virginia and West Virginia. The storms were expected to pummel Boston just before the marathon Monday.

"Across the northern mid-Atlantic and into southern New England, this could be a case where strong winds are produced with a minimal amount of thunder and lightning. It is possible that the downpours and gusty thunderstorms track across Boston just prior to the start of the Boston Marathon on Monday morning," Pydynowski said.

The storm will then move on to the central and eastern U.S. later this week, causing flooding.

"The severe threat will begin in the Plains on Wednesday then progress eastward, arriving at portions of the Atlantic coast late Friday. There is the potential for all modes of severe weather from damaging winds to large hail, flooding downpours and tornadoes associated with thunderstorms throughout this entire area," AccuWeather meteorologist Jake Sojda said.

Storm clouds loom over a grain elevator in Convent, Louisiana, June 11, 2018. REUTERS/Jonathan Bachman