Over 12 million Americans were on alert Sunday as a major storm system headed east, following at least three weather-related deaths in Oklahoma. 

A disaster is unfolding in the Heartland, with rivers still rising across several states after the multi-day severe weather outbreak.

The same states in the Midwest and South that were slammed by deadly tornadoes braced for round two as a once-in-a-generation weather event strikes again.

Multiple tornadoes reported across the South and Midwest have caused “catastrophic” damage.

Millions of Americans are on edge as a powerful storm system slams parts of the South and Midwest.

Damaging winds and severe thunderstorms are expected overnight.

A spring storm system will move east over the next three days, bringing a variety of dangerous and life-threatening weather from the Heartland to the East Coast.

The latest on the dangerous wildfires spreading in the Carolinas as tornado warnings go into effect in the heartland.

"GMA" reflects on the devastating EF-4 tornado that struck Rolling Fork, Mississippi, and how the community has worked to rebuild.

The tornado took down power lines and damaged at least one home, but did not do the same damage as the EF-4 that devastated the town two years ago.

While tornado watches are in effect, damaging wind gusts and large hail remain the primary hazards from any severe thunderstorms on Sunday.

Two EF-4 tornadoes were reported in Arkansas, with 170 and 190 mph wind speeds. Over 1,000 storm damage reports have come in from at least 24 states.

A three-day tornado outbreak tore through nine states. At least 43 people were killed in tornadoes in Missouri.

Megan Scarano from ABC affiliate WBMA reports from the destruction in Talladega, Alabama.

There were at least 60 tornadoes throughout the Midwest during a deadly storm system over the weekend. It’s expected to move toward the East Coast.  

Stephanie Fox, national spokesperson for the American Red Cross, joins ABC News Live to discuss the recovery efforts after a devastating tornado outbreak across multiple states.

Storms have prompted more than 660 reports of severe weather across more than a dozen states.

Tornadoes left a trail of destruction in at least six states and the same storm system brought gusty winds that fueled more than 130 wildfires in Oklahoma.

The state of emergency in Missouri remains in place after storms erupted across the state Friday night.

Jeff Smitherman, the director of an Alabama emergency management agency, joins ABC News live to discuss the high-risk alert for potential tornado outbreaks in Alabama and Mississippi.

Harold Copenhaver, the mayor of Jonesboro, Arkansas, joins ABC News live to discuss the dangerous tornadoes touching down in northeastern part of the state.

A confirmed EF-2 tornado touched down in Seminole County on Monday, with winds up to 115 mph. The tornado damaged or destroyed several homes, but no injuries were reported.

By Wednesday, the storm system will move to the East Coast, bringing heavy rain and damaging winds from Georgia to New York.

Two men on a boat were stuck in the middle of a storm along the Gulf Coast near Winnie, Texas.

A tornado watch has been issued for 5 million people in parts of east Texas, much of Louisiana, and southern Mississippi.

Communities around Houston, Texas, were hit hard by an outbreak of tornadoes, and more storms are due Sunday across the region. ABC News' Morgan Norwood reports from Brandon, Mississippi.

An apparent tornado touched down in a small Northern California city Saturday, flipping cars, causing significant damage and sending several people to the hospital.

An apparent tornado touched down in Scotts Valley, California, on Saturday, causing several people to be injured, police said.

Rare weather event hits Scotts Valley, California, when a twister made landfall, leaving behind a trail of destruction and several injured.

The National Weather Service called the tornado, which touched down in Scott’s Valley, California, and caused significant damage, an EF-1 tornado.

The storm was near Granite, a town with a population of about 1,600, at about 3:37 a.m. CST, the service said.

Ahead of Milton making landfall in Florida, the hurricane spawned more than 20 reported tornadoes statewide. They caused significant damage as millions braced for the powerful storm.

Hurricane Milton has spawned a destructive tornado outbreak, with more than 30 reported twisters on Wednesday ahead of landfall.

The rare weather event in the area tore roofs off buildings, left some without power and flipped over a car.

Jack Jones shared a video of him singing Ed Sheeran's hit, "Perfect," as the newlyweds danced together in darkness caused by a power outage.

Numerous tornadoes were reported in Maryland and northern Virginia Wednesday night, knocking downing trees and power lines.

A 3-year-old child died Wednesday when a tree fell on a house during a tornado in Michigan. Thursday night, there is an impending risk of further storms along the I-95 corridor.

Several counties in Maryland are under tornado warnings tonight, with damage from the storms already reported in Montgomery County.

The National Weather Service issued five different tornado warnings across Maryland due to the severity of the storms.

At least one person was injured as a possible tornado struck Sanderson, Texas, law enforcement said.

Severe weather in the U.S. has been very active of late, with wind gusts over 70 mph and tornadoes causing significant damage and claiming 22 lives across five states over the Memorial Day weekend.

The most active spring for severe weather in 13 years continued Tuesday with wind gusts of more than 70 mph and thunderstorms prompting new tornado warnings in Texas.

A new round of severe storms is expected to hit Texas after the deadliest tornado since 2015 hit the state.

Severe storms over the weekend led to the deaths of at least 18 people across Texas, Oklahoma, Arkansas, Missouri and Kansas.

The dangerous weather caused chaos in Texas with multiple deaths.

When a tornado ripped through Greenfield, Iowa, last week, Fire Chief TJ Oder said his house took a direct hit but his family was saved by a private tornado shelter.

ABC News Meteorologist Somara Theodore gives the latest update on a dangerous storm system moving east amid record Memorial Day weekend travel.

Severe weather is forecasted from Austin, Texas, to Chicago as people travel for Memorial Day weekend.

Families are investing in shelters in Tornado Alley when other options are too far away.

There were over 200 severe storm reports from New York to Texas. A fifth person was killed in what is believed to be a tornado-related incident about 25 miles from Greenfield, Iowa, officials said.