More than 70 million Americans face a severe weather threat this week.

Arkansas was especially hard hit. It faced six suspected tornadoes, large hail— with some pieces the size of a softball — and strong winds Monday night. Although they cleared up Tuesday morning, another round of storms is expected for the afternoon and throughout the night.

Severe storms caused minor structural damage, flash flooding and power failures but no reported injuries, according to the Arkansas Democrat-Gazette. On Twitter, people posted videos of barns getting ripped up by the storm, intense flashes of lightning brightening the night sky and hail held up to baseballs, ping-pong balls and their own hands to scale.

NewsNation local affiliate KARK reported that the University of Central Arkansas is canceling classes because of a power outage and isolated flooding on its campus stemming from the powerful series of storms.

On Tuesday, Arkansas, Mississippi and Tennessee were all under a severe thunderstorm watch until 4 a.m., the National Weather Service said in a tweet. In some places, including Dallas and Austin in Texas, Kansas City, Missouri and Des Moines Iowa had storm warnings upgraded from a level three to a level four, meaning a “moderate risk.”

Some places are seeing winter storm warnings, such as Montana, or North and South Dakota, which could see blizzards with over two feet of snow possible.