"This line is capable of producing damaging winds, large hail and possibly an isolated tornado", the weather service said.
Suspected tornadoes also were reported overnight in various parts of Alabama, including Highland Lakes, Greystone and American Village in Shelby County and lake Purdy at Grants in Jefferson County. Trees were pulled up by the roots, roofs torn off buildings and the cinder block foundation was all that was left of a mobile home in the town, which is southeast of Waco.
Deaths were reported across Mississippi, Texas and Louisiana.
In East Texas, the Angelina County Sheriff's Office said an 8-year-old and a 3-year-old died when strong winds toppled a tree onto the back of their family's auto in Lufkin while it was in motion.
After arriving at the scene, police were able to determine "that two children age 8 and 3 were trapped in the back seat of the vehicle under the tree".
Mississippi's Monroe County was also hit hard, as multiple homes as well as the local fire station were destroyed, reported CNN. The center said it expects the threat of severe weather to increase throughout the day.
ABC News reported two more deaths after a tornado ripped through Hamilton, Mississippi. As a result, the National Weather Service has issued a wind advisory for all 21 counties in New Jersey, as well as for New York City.
"Heavy rainfall may hide this tornado".
The same system caused damage in Columbus, Mississippi. The vehicle was on a back country road in Pollok, Texas, about 150 miles (241 kilometres) southeast of Dallas. Homes were damaged about 250 miles (402 kilometers) to the north in Glencoe, and there's scattered damage south of Birmingham. The parents, who were in the front seats, were not injured.
Winds reached 60 miles per hour in Binghamton, the weather service said, as lines of severe thunderstorms rolled into the Northeast Sunday night.
According to Capt Alton Lenderman of the Angelina County Sheriff's Office, the tree "flattened the auto like a pancake", but the parents, who were riding in the front of the vehicle, were not injured.