At least 40 people in seven states have died amid the severe weather outbreak, officials said Sunday.

At least 12 deaths were reported in Missouri, the most of any state, officials said.

On Sunday morning, Alabama Gov. Kay Ivey said at least three people were killed in her state on Saturday.

"Yesterday's severe weather impacted most of Alabama," Ivey said in a statement. "Unfortunately, we have learned of the loss of at least two of our fellow Alabamians -- one life in Plantersville and one in Winterboro."

Ivey said 52 of Alabama's 67 counties reported damage from the severe weather outbreak and that a damage assessment was continuing.

"The sun has risen in Alabama, though," Ivey said. "We pray for those lives we lost, as well as those who were injured. And we pray for our first responders, emergency management officials, and linemen who are doing incredible work on the ground right now."

At least eight deaths were reported in Kansas; six people in Mississippi were killed; four people perished in Texas; three people died in Arkansas; and four people were killed in Oklahoma, officials said.

ABC News' Victoria Arancio

As the cross-country storm continues to spread across the United States, cities north of Tampa, Florida, are now under tornado warnings.

Zephyrhills, Pasadena Hills and Crystal Springs are under alert until 7:30 p.m. ET, according to the National Weather Service.

Mississippi Governor Tate Reeves shared a storm update Sunday afternoon after signing a state of emergency declaration Saturday night.

The governor said preliminary information shows as many as 12 tornadoes could have ripped through the state in the cross-country storm.

The storm left six dead and 27 injured in Mississippi, but the three people reported missing were found alive, Reeves said.

Twenty-three counties in the state are reporting damage and 12 filed emergency requests, the governor said.

-ABC News' Darren Reynolds

President Donald Trump took to his social media platform on Sunday to say that the White House is monitoring the spate of tornadoes and storms impacting the Midwest and South.

Thirty-seven people have been killed in the cross-country storm system, according to officials.

Trump said the National Guard has been deployed to Arkansas.

"My Administration is ready to assist State and Local Officials, as they help their communities to try and recover from the damage," Trump wrote.

"Please join Melania and me in praying for everyone impacted by these terrible storms!" the president added.

-ABC News' Hannah Demissie

The Storm Prediction Center said that numerous significant tornadoes, some of which could be long-track and potentially violent, are expected and cities in the high risk areas include Hattiesburg, Jackson, Tuscaloosa and Birmingham.

The most dangerous tornado threat should begin Saturday during the late morning to early afternoon hours in Louisiana and Mississippi before spreading into Alabama late afternoon into the evening, followed by the western Florida panhandle and into western Georgia through late Saturday night.

There were 23 reported tornadoes overnight across four states – Missouri, Arkansas, Illinois and Mississippi as the severe weather outbreak continues into Saturday. Winds gusted up more than 80 mph causing damage in the Midwest from Missouri to Wisconsin.

Georgia Gov. Brian Kemp issued a state of emergency effective noon Saturday in preparation for severe weather moving into the state this evening and into the morning.

The severe storms are expected to be weaker on Sunday as the storms reach the East Coast from Florida to the Mid-Atlantic.
Damaging winds, large hail and brief tornadoes on Sunday afternoon will be possible for the Southeast, while heavy rain and damaging wind threat will reach the Northeast Sunday evening into the overnight.

The severe weather outbreak is all part of a major cross-country storm system that is also prompting fire danger and red flag warnings across the Plains.