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

Over the past 24 hours, more than 40 reported tornadoes have swept across eight states in the Midwest and South -- and the dangerous severe weather threat continues.

The eight states with reported tornadoes in the past day are Alabama, Missouri, Arkansas, Mississippi, Louisiana, Illinois, Indiana and Tennessee.

Overall, there have been more than 500 reports of severe weather since late Friday, from the Midwest into the South, including not only tornadoes, but damaging wind gusts and large hail.

Across the South, Tornado watches remain in effect in portions of Mississippi, Alabama, Louisiana, Tennessee and Georgia as a line of powerful storms continues to sweep east.

A tornado watch designated a "Particularly Dangerous Situation" remains in effect for much of Alabama and portions of Mississippi and Louisiana until 8 p.m. CT. The worst of the tornado threat will be over after this.

From eastern Tennessee, including Knoxville, into northwestern Georgia, a tornado watch remains in effect until 1 a.m. ET. Additional watches could be posted in the coming hours for points east, across George and into the Florida Panhandle.

There is also the threat of additional severe thunderstorms bringing potentially damaging wind gusts and large hail. Any stronger, slow-moving thunderstorms could also bring torrential rain and frequent lightning.

Dangerous flash flooding is also a concern. Flash flood warnings are in effect from southern Mississippi through central Tennessee.

-ABC News' Daniel Peck