A woman died Saturday in St. Louis when a tree fell on her car during severe weather, according to police.

St. Louis Police Sgt. Charles Wall told CNN in an email the woman had been "parked and seated inside of the vehicle when a tree fell on top of it during severe weather." The 33-year-old woman was "pronounced deceased," Wall wrote.

There were at least eight reports of hail in Missouri on Saturday, including some reports house windows were broken by the frozen pellets, according to the National Weather Service. There were also several reports of severe wind, including in St. Louis, where large trees were uprooted, the NWS said.

Severe weather is expected to continue affecting several parts of the United States ahead of the Fourth of July. One hundred million people are under severe weather threats from the eastern Rockies through the Ohio and Tennessee River Valleys and into the mid-Atlantic region.

There is a Level 3 of 5 risk for much of Kentucky and northern Tennessee, impacting five million people in cities like Louisville, Lexington, Nashville, where damaging wind, large hail and a few tornadoes are likely.

On Sunday morning, storms already began appearing in Ohio, Kentucky, Illinois and Iowa. The storms are expected to continue into the afternoon and evening.

A flash flood warning was put into place for nearly five million people in Illinois, including residents of Chicago, due to thunderstorms and heavy rain. The rain caused delays and cancellations for some sporting events scheduled for Sunday in the Windy City: The Chicago Cubs had to push their game against the Cleveland Guardians back by several hours, and NASCAR had to alter its racing slate and truncate one of its scheduled races.

And 63 million people are under a combination of heat advisories and excessive heat warnings, with severe heat spreading from the Southwest to the Southeast. Around 70% of the country's population, about 225 million people, will experience high temperatures above 90 degrees. And around 8% of the population, or 26 million people, will see highs above 100 degrees.