21 killed and dozens are hospitalized as tornadoes and dangerous storms tear through the South and Midwest

(CNN) — At least 21 people died after devastating storms and violent tornadoes scraped the South and Midwest Friday into early Saturday and millions more people were threatened by more severe weather Saturday afternoon.

Among the victims were four people who were killed in structural collapses in Illinois. Three of the fatalities followed the collapse of a residential structure in Crawford County, said Illinois Emergency Management Agency spokesperson Kevin Sur, while the fourth person died after the roof collapsed at the Apollo Theatre in Belvidere.

More than 50 preliminary tornado reports were recorded Friday in at least seven states, including in Arkansas, where storms killed five people -- four in the small city of Wynne and another person in North Little Rock, local officials said.

Three people were killed in Indiana by a storm Friday night that damaged homes and a volunteer fire department near Sullivan, a city about a 95-mile drive southwest of Indianapolis, State Police Sgt. Matt Ames said.

In Madison County, Alabama, one person died and five were injured overnight, officials said during a news conference Saturday morning.

In Pontotoc County, Mississippi, one person died and four others were injured, according to the Mississippi Emergency Management Agency.

Allen Strickland, the McNairy County, Tennessee, director of emergency management, also confirmed there were seven deaths in the county, which is located in southern Tennessee between Nashville and Memphis.

At least 50 people were sent to hospitals in Arkansas' Pulaski County, where a tornado roared through the Little Rock area Friday, county spokesperson Madeline Roberts said. Five others were hospitalized after a tornado touched down Friday in Covington, Tennessee, according to a spokesperson for Baptist Memorial Health Care. Roads were left impassable.

'It just came out of nowhere'

In Little Rock, "close to 2,600 structures have been impacted," Mayor Frank Scott Jr. told CNN on Saturday.

At last 2,100 residents in the pathway of the tornado were affected, he said. Neighborhoods and commercial businesses were flattened, while vehicles flew across the air, the mayor described.

"It's by the grace of God nobody in Little Rock was killed," Scott said, adding the storm passed through the city at a time many people had not yet returned home from work, which was fortunate timing. "Many people were not at their homes. If they were, it would have been a massacre."

At least a dozen tornadoes were reported in Arkansas, including in the Little Rock area.

More than 34,000 people in the state were still without power Saturday afternoon, according to the tracking website poweroutage.us.

William Williams, who told CNN affiliate KATV he's an employee at a Kroger supermarket in Little Rock, said he's "thankful to be alive" after a tornado rolled near the area while he was working Friday afternoon. He took shelter inside the store and went outside afterward to see people injured, including a woman he said had a severe leg injury.

"Everything happened in like five seconds. It came -- boom," Williams told KATV. "You could hear a lot of commotion and stuff. ... I go outside, and it is crazy. People had blood all over their faces. ... I'm just thankful that I'm alive."

About 100 miles east of Little Rock, the city of Wynne was "basically cut in half by damage from east to west," Mayor Jennifer Hobbs told CNN Friday evening.

Some houses in Wynne -- home to about 8,000 residents -- were completely crushed into piles of wood while others had their roofs ripped off, exposing the interiors of homes littered with storm debris, drone footage provided to CNN by Ray Sharp show. Many trees toppled, making what appears to be residential roads impassable and damaging structures.

Friday's severe storms came a week after severe weather walloped the Southeast and killed at least 26 people. An overnight tornado, which makes people most prone to extensive damages, leveled much of Rolling Fork, Mississippi, where estimated maximum winds of 170 mph roared.

Theater roof crumbles amid storms

More than 200 people were inside the Apollo Theatre in Belvidere in northern Illinois for an event when its roof collapsed Friday night, leaving one person dead and dozens injured, the city fire chief said. The collapse came as a line of storms packing 50 mph winds and dumping hail moved through the area, according to officials and the National Weather Service. It wasn't immediately clear whether the storm caused the theater's roof to crumble.

Twenty-eight people were taken to hospitals because of the collapse, Belvidere Fire Chief Shawn Schadle said.

Meanwhile in Indiana, the storm ripped through Sullivan County, trapping a local official's wife inside their home until their son rescued her.

Jim Pirtle, the emergency management director for the county, told CNN his house and many others were destroyed Friday night.

"I called (my wife) 45 minutes before it hit. I told her, 'Robin, you need to go somewhere.' We don't have a basement," Pirtle said. "I was on the phone with her and she was crying, 'Jim, I love you' and it started tearing the house apart.

"We got hit bad," Pirtle said speaking by phone from Florida, adding he was working with emergency officials remotely.

"I'm not sure about fatalities yet," he added. "We still got people missing."

Houses in Sullivan, a city home to about 4,000 residents, multiple houses were severely damaged due to the storm, Mayor Clint Lamb said.

"We need all citizens to stay safe and stay put," Lamb said in a Facebook post overnight. "First responders need clear streets so they can tend to affected areas. Please pray for the Sullivan families and public safety personnel."

Howard, Johnson and Sullivan counties have been hit hard by storms, according to meteorologist Andrew White with the Indianapolis Office of the National Weather Service.

However, the damage in Howard County was minor and reported no injuries, according to emergency management director Janice Hart.

Indiana Gov. Eric Holcomb on Saturday declared a disaster emergency for Sullivan and Johnson counties, and said Indiana officials were working with FEMA to assess damages.

More than 50 million under severe weather alerts

More than 50 million people are under threat for severe weather Saturday evening.

There are severe thunderstorm watches in effect for parts of the Southeast, including southern Alabama, parts of the Florida Panhandle, and south Georgia until 8 p.m. ET.

Severe thunderstorm watches are also in effect for in parts of the Northeast, including much of Pennsylvania and parts of New York until 8 p.m. ET.

Severe storms are bringing damaging winds into the evening, which could affect some of the big Northeast cities, including Philadelphia, New York, and Boston in the evening.

On Friday, large hail proved to be dangerous when it bombarded northern Illinois, cracking and denting cars' windshields, according to a Facebook post from the Fulton County Emergency Services and Disaster Agency.

About 78 miles southeast of there, several businesses were "basically destroyed," Sheriff Jack Campbell told CNN, and up to 40 homes were damaged around Sherman, less than 10 miles north of Springfield.

More than 490,000 customers were without power across Pennsylvania and Ohio Saturday afternoon, according topoweroutage.us.