WENTZVILLE, Mo. -- Severe storms swept through eastern and southeastern Missouri Sunday afternoon causing extensive damage and as yet unconfirmed reports of tornadoes.
Reports of damage include a seed store destroyed in Morley, a grain elevator knocked down in Oran and the roof blown off of the Heritage School in Wentzville.
The same system killed a brother and sister in a farmhouse in Washington County, Illinois, where National Weather Service surveyors confirmed a powerful EF-4 tornado had touched down. No fatalities or serious injuries have been reported in Missouri.
Ameren Missouri is reporting 19,700 customers out of power as of 5 Sunday evening.
(story contributed by Missourinet)
(CNN) -- Severe weather erupted throughout the Midwest on Sunday afternoon, with tornadoes tearing through several cities and a storm forcing fans to evacuate the stands during an NFL game.
"We saw trees down, houses with their roofs completely torn off. I saw a lot of people in distress with their homes destroyed," said Jack Lance, who lives in Pekin, Illinois. "It wasn't a pretty sight."
Video above of damage in Washington County, Illinois provided by WMBD
At least three people died in Illinois as a result of the severe storms, said Jonathon Monken, director of the Illinois Emergency Management Agency.
In two communities, storms destroyed at least 70 homes, he said. Rescuers are trying to reach people trapped in their basements. And one hospital in Peoria is treating 37 patients with injuries.
More than 60 tornadoes had been reported throughout the region as of 5:10 p.m. Sunday, the National Weather Service said.
As a tornado neared his home in Washington, Illinois, Anthony Khoury prayed and recorded a video of the dark twister churning toward him.
"The tornado happened in my backyard, and you can hear people screaming," he told CNN's iReport. "We were freaking out."
While his house survived the storm, Khoury said others in the neighborhood weren't as lucky.
"It was complete destruction," he said. "There are people in the streets crying."
Photos of the storm-damaged city showed cars flipped over and massive piles of debris.
Peoria Mayor Jim Ardis said his city was planning to send aid to help storm recovery in nearby Washington, where a tornado hit what he described as a "very densely populated area."
"You can see the pictures," he said. "It's just absolutely unbelievable."
Officials delayed the NFL game between the Chicago Bears and Baltimore Ravens for nearly two hours as storms approached Chicago, warning spectators to leave the stands at Soldier Field and head for covered areas.
"The rain started coming, the skies got black, the wind was insane, and they evacuated us to underneath the concrete concourse," said Jim Arnold, who was at the game with his 11-year-old daughter.
"We've been through 15-degree-below weather and winds, but never anything like this," Arnold said. "The winds gusted at 70 mph, and the winds and the rain were horizontal and everybody was running. It was just crazy."
Fans returned to their seats and the game resumed mid-afternoon after the storm passed.
But other parts of the region still faced the threat of more severe weather, forecasters warned.
Tornado watches have been issued from Michigan to Missouri, CNN meteorologist Karen Maginnis said. Severe weather threatened 26 states and more than 100 million people, she said.
Forecasters said there was a possibility of intense tornadoes, large hail up to 2 inches in diameter, and damaging wind gusts -- some of them greater than 80 mph in and near the watch areas.
The watch area also includes Detroit and Indianapolis.
"These storms having been moving so fast today, it's been hard to keep up," said storm chaser Tony Laubach, who spoke to CNN as he watched a tornado touch down outside Lebanon, Indiana.
In a Twitter post, Indiana State Police shared a photo of twisted metal, piles of debris and the shell of a school building.
Many people are without power across the state, police said.
In Oak Lawn, Illinois, a wind gust of 86 mph was recorded as a severe thunderstorm rolled through the area.
At least six trucks overturned on Illinois highways due to high winds, the Ogle County Sheriff's Office said.
This is a particularly dangerous situation, the National Weather Service said in a bulletin released Sunday morning.
And a tweet from the weather service in northern Indiana was even more ominous: "The worst decision you could make today is to ignore a severe/tornado warning. These storms will be nasty."
A tornado watch means that weather conditions exist that can produce tornadoes and severe thunderstorms. Conditions are favorable for long-tracked, significant tornadoes across this watch area, the Storm Prediction Center said.
CNN's George Howell, Sean Morris, Fredricka Whitfield, Don Lemon, Jareen Imam, David Ruff and Taylor Ward contributed to this report.