A three-day severe storm system that brought hail, high winds and some tornadoes to the Kansas-Texas corridor moved slowly eastward into the Deep South on Thursday, killing three people and leaving more than 100,000 households across four states without power.

The National Weather Service warns of several possible tornadoes and extensive wind damage across the central Gulf Coast states, South and Tennessee Valley – especially in Louisiana and Mississippi. Excessive rain is possible from the central Gulf Coast to the Ohio Valley.

The system was expected to reach the East by Friday morning, and storms would intensify from Florida through the Mid-Atlantic by the afternoon, the weather service said.

A Mississippi man was killed Thursday afternoon when his car hit a tree on a highway south of Philadelphia, Mississippi, Neshoba County Coroner John Stephens told local news outlets. Another man was also killed while driving in the storm near the rural town of Gillsburg in southwest Mississippi, WLBT-TV reported.

A woman in Alabama was killed when a tree fell on her mobile home in St. Clair County, according to the local sheriff's office. The woman's 10-year-old son suffered minor injuries.

A tornado watch reached from coastal Louisiana into central Mississippi and flood warnings reached as far north as central Indiana. Multiple tornadoes and storms swept across parts of Mississippi on Thursday afternoon and evening, leaving downed trees and tens of thousands of households without power.

There were widespread power outages also reported in Alabama, Louisiana and Texas on Thursday night.

Damaging winds offer the biggest threat from the Florida Peninsula to the Mid-Atlantic. "The most likely area for tornadoes may be close to the Carolina coast, where a breeze from the Atlantic Ocean may impart extra spin in the low levels of the atmosphere," according to AccuWeather Senior Meteorologist Dan Kottlowski.

The storm promises no let-up as it churns across the Deep South. "The greatest risk of severe weather is in the Gulf Coast states today, and in the Southeast Atlantic

Coast states from Virginia to Florida on Friday," the weather service says. The main threat on Thursday, the weather service says, will be damaging wind gusts and several tornadoes.

The thunderstorms and heavy rain also pose a risk of flash flooding over much of the eastern half of the U.S., from the northern border with Canada south to Georgia, in the next two days.

Contributing: The Associated Press