Two people are dead and 1.1 million are without power after severe storms battered the Eastern U.S.
Residents across multiple states are also dealing with downed trees, debris-filled streets and damaged homes and cars.
In Florence, Alabama, police said a 28-year-old was struck by lightning and died, according to the Associated Press.
In South Carolina, a 15-year-old boy who arrived at his grandparents' house was hit by a falling tree and killed when he got out of the car, the Anderson County Office of the Coroner confirmed, according to AP.
Nearly 30 million people in the mid-Atlantic region were under a tornado watch Monday, in an area stretching from New York to Kentucky. Severe storms were forecast from North Carolina to Alabama.
The FAA warned that it would be rerouting flights around the widespread storms, affecting air travel across the Northeast.
Ground stops paused air traffic at East Coast airports Monday, including in Washington, D.C., Maryland, North Carolina, Pennsylvania and New Jersey.
About 10,000 flights were canceled or delayed on Monday, according to FlightAware. Another 800 flights were delayed and 300 canceled on Tuesday morning.
Commuter rail networks in Maryland and Virginia warned of cancellations and possible delays as a result of the weather. Government employees in the Washington, D.C., area were sent home early Monday night.
Gusts of winds near Washington, D.C., on Monday evening hit close to 60 miles per hour.
The severe weather outbreak follows several days of active weather. More than 300 severe weather reports were filed with the National Weather Service on Sunday, predominantly along the Gulf Coast. More than 200 reports of severe weather were filed on Saturday, including several for winds exceeding 80 mph in Kansas.
Fueling the storms is warmth and humidity that will cause heat indexes to rise to 100 in some areas.
The storm system is separating relatively mild conditions in the Midwest from oppressive heat in the South. Excessive heat warnings have been issued from Georgia and Florida to West Texas.
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