At least five people have died in Bollinger County, according to local Sheriff Casey Graham.

"Several of our communities in Bollinger County, specifically the Grassy and Glenallen areas, were hit with what appears to be a significant tornado early this morning," Graham said in statement posted on Facebook.

Images show that the village of Glenallen sustained heavy damage. It sits just 4 miles from Marble Hill, the county seat.

Search and rescue efforts remain ongoing, Sgt. Clark Parrott of the Missouri Highway Patrol, told ABC News on Wednesday morning.

-ABC News' Will McDuffie

As the Earth's temperature climbs, so does the threat of extreme weather events such as drought, wildfire, hurricanes and tornadoes -- all occurring more frequently and at higher magnitudes, according to climate scientists.

More violent and widespread tornado activity -- like the line of severe storms in recent days that killed dozens of people -- is expected in the future as global warming persists, experts told ABC News.

While such events have occurred in the past, the evidence points to climate change contributing to the frequency and magnitude of tornado behavior, experts told ABC News.

"This is a representation of what we might perhaps expect to happen in a particularly active tornado season as we move forward in a warming climate regime," said Jana Houser, associate professor of meteorology at Ohio State University, of the recent deadly tornado activity.

Read more here.

The National Weather Service has issued a tornado watch for several regions under threat of severe storms on Wednesday.

Included in the advisory are central and southern Indiana, north-central Kentucky and southwest Ohio. The formation of tornadoes could be “likely” in cities like Indianapolis, Cincinnati and Louisville, according to the NWS.

The threats include “widespread" damaging wind gusts up to 70 mph, the advisory states.

The tornado watch is in effect until 5 p.m. ET.

An unspecified number of injuries and fatalities have been confirmed in Missouri's Bollinger County after a tornado hit the Glenallen area, according to the Missouri State Highway Patrol.

At least nine other tornadoes had already been reported across Iowa and Illinois, including a "large and extremely dangerous tornado" that touched down near Canton, Illinois, on Tuesday evening, according to the National Weather Service.

Missouri Gov. Mike Parson announced he will visit hard-hit Bollinger County.

Parson will "assess damage and learn what resources will be needed during recovery" in the rural county in the state's southeast, he said in a tweet.

"We appreciate the work of our first responders and the many neighbors who reached out to help their neighbors, and our prayers are with the loved ones of those who were killed in the storms," the governor said.